Method of unloading dry bulk materials from a dry bulk tank

ABSTRACT

A dry bulk tank and a method of carrying a load and discharging a load therefrom. The dry bulk tank includes a tank assembly having a first wall that bounds and defines a first compartment for carrying a load therein and a second wall spaced outwardly from at least a portion of the first wall; wherein a second compartment is defined between the first wall and the second wall. The tank assembly includes an air piping system that is selectively actuated to place the first compartment and the second compartment under equal air pressure. In one example the air piping system pumps air into the first compartment and the second compartment. In another example the air piping system evacuates air from the first and second compartments.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/648,694, filed on Mar. 27, 2018; the disclosure of which isincorporated herein by reference.

BACKGROUND Technical Field

The technical field is related generally to bulk tankers or bulk orpneumatic tanks/trailers having a plurality of hoppers. Moreparticularly, the technical field is related to such a tank or trailerhaving a first compartment for transporting a load therein, a secondcompartment that is located in abutting contact with the firstcompartment; and a system for placing the first compartment and secondcompartment under substantially similar or substantially equal pressure.

Background Information

Bulk tankers and bulk tank trailers or pneumatic tank trailers areamongst the many types of vehicles used for hauling materials overhighways and the like. These tankers or tank trailers are used totransport bulk materials, particularly dry, particulate-type bulkmaterials from one location to another. The types of materialtransported in these vehicles may include foodstuffs such as sugar andflour, chemicals, silica, plastic pellets, and building materials suchas sand or dry cement. The term “trailer” will be used throughout therest of the specification to identify a bulk tank trailer that is usedto transport materials. However, it should be understood that the terms“trailer”, “bulk tank trailer”, “tanker”, “tank”, “truck”, “vessel” or“vehicle” may be used interchangeably in this description.

The tankers or tank trailers typically include several hoppers or conesthat facilitate the discharge of the bulk material from within the tankinto a discharge pipe through which pressurized air is pumped todischarge the material to a rear end of the trailer. Valve assembliesare typically located at the bottom of the hoppers whereby the hoppersmay be opened or closed to respectively allow the flow of the bulkparticulate material from the hoppers into the discharge pipe and to cutoff this flow.

The tank itself is a closeable vessel that has a number of manholesprovided in a top region of the tank body. Each manhole includes a coverfor closing off access to the manhole. The covers are removed whenmaterial is to be loaded into a storage compartment defined in theinterior of the tank. The tanker or tank trailer is moved into a loadingbay and is positioned so that the one or more manholes are aligned withoverhead pipes or hoses that are connected to a source of the drymaterials to be carried in the vessel. Once the tank's storagecompartment is filled to the desired level, the covers are replaced onthe manholes and the tanker or tank trailer will travel to itsdestination.

As indicated above, the bottom region of the tanker or tank trailer isformed into a plurality of hoppers that each terminate in an elongatedischarge pipe that extends from the first hopper through to a rear endof the vessel. Each hopper connects via a T-connection to the dischargepipe. A butterfly valve and an aerator are typically provided proximatethe T-connection between the hopper and the discharge pipe. The aeratorskeep the dry materials aerated and help ensure that the materials arefluidized, i.e., that they will flow in a similar manner to a liquid.The butterfly valves control whether there is fluid communicationbetween the hopper and the discharge pipe. When the tanker arrives atits destination, the operator will connect the end of the discharge pipeto an inlet for a storage vessel for the transported dry materials. Theoperator will go through a series of steps of pressurizing the dischargepipe, aerating the load, opening the butterfly valves sequentially andemptying the transported material from the tank via the discharge pipe.The pressure within the tank and the discharge pipe has to be keptwithin a certain range to ensure that all the material will be evacuatedfrom the storage compartment defined by the tanker body. Once basicallyall material has been removed from the storage compartment, the operatorwill use pressurized air fed from a top region of the tank to blow outthe storage compartment to clean the same and will sequentially closethe hoppers, shut down the aerators and stop the pressurization of thedischarge pipe in a predetermined sequence that ensures safety of theoperator and integrity of the tank. In other instances, instead of thetank being pressurized to remove the dry materials therefrom, a vacuumsource may be connected to the end of the discharge pipe and a vacuumwill be applied to the discharge pipe to suck the dry materials from thehoppers.

Such tankers or trailers typically include a relatively substantial orlarge frame on which the tank/hoppers are mounted. Such frames arerelatively heavy, which may, for instance, decrease gas mileage orreduce the amount of cargo that may be carried in the tank while stayingwithin government weight regulations.

SUMMARY

In one aspect, the present disclosure may provide a dry bulk tank forcarrying a load; said dry bulk tank comprising a tank assembly; a firstwall provided on the tank assembly; said first wall bounding anddefining a first compartment that is adapted to carry a load therein; asecond wall spaced outwardly from at least a portion of the first wall;wherein a second compartment is defined between the first wall and thesecond wall; and an air piping system engaged with the tank assembly;wherein the air piping system is selectively actuated to place the firstcompartment and the second compartment under substantially similar orsubstantially equal air pressure.

In one example the tank assembly comprises a vessel that is circular inlateral cross-section. In another example the tank assembly includes afront end housing and a central section that extends rearwardly from thefront end housing; and wherein each of the front end housing and thecentral section are circular in lateral cross-section. The firstcompartment is defined in the central section and the second compartmentis defined partially in the front end housing. In other embodiments thesecond compartment is also defined partially in the central section.

In other embodiments, the tank assembly further includes a rear endhousing that extends rearwardly from the central section; and whereinthe rear end housing is circular in lateral cross-section and whereinthe second compartment is further defined at least partially in the rearend housing. The second compartment is sealed from contact with airlocated outside of the tank assembly. The air piping system places thefirst compartment and second compartment in fluid communication witheach other. In one embodiment the air piping system is activatable toplace the first and second compartments under pressure and may place thefirst and second compartments under substantially similar orsubstantially equal pressure simultaneously. In other embodiment the airpiping system is activatable to place the first and second compartmentsunder vacuum. The air piping system may be activatable to simultaneouslyplace the first and second compartments under substantially similar orsubstantially equal vacuum. When the air piping system is activated theair pressure on a first side of a portion of the first wall in the firstcompartment is substantially similar or substantially equal to an airpressure on a second side of the portion of the first wall in the secondcompartment.

In one embodiment the dry bulk tank has a central section includes atleast one hopper extending downwardly from a bottom of the centralsection; and wherein an interior of the at least one hopper forms a partof the first compartment; and wherein a lower region of the at least onehopper extends for a distance below the second compartment.

In another aspect, the present disclosure may provide a method oftransporting and unloading dry bulk materials comprising providing a drybulk tank trailer that includes a first compartment and a secondcompartment; wherein the first and second compartments are located onopposite sides of a portion of a wall that bounds and defines the firstcompartment; loading a quantity of dry bulk materials into the firstcompartment; substantially equalizing air pressure in the firstcompartment and in the second compartment; and unloading the dry bulkmaterials from the first compartment while the first and secondcompartments are under substantially similar or substantially equal airpressure.

In one embodiment substantially equalizing air pressure in the firstcompartment and the second compartment includes pumping air into thefirst compartment and the second compartment through an air pipingsystem. The pumping of air into the first compartment and the secondcompartment occurs substantially simultaneously and pumping the air intothe first compartment and the second compartment continues until the airpressure in each of the first and second compartments is from about 10Psi up to about 15 Psi.

In another embodiment substantially equalizing air pressure in the firstcompartment and the second compartment includes vacuuming air from thefirst compartment and vacuuming air from the second compartment untilthere is substantially similar or substantially equal air pressure inthe first and second compartments. The substantially equalizing of theair pressure includes simultaneously vacuuming air from the firstcompartment and from the second compartment.

In one example the method further comprises forming the dry bulk tanktrailer as a vessel that is generally circular in cross-sectional shapewhen viewed from a front end or a rear end. In another example, theforming of the dry bulk tank includes providing a central section;providing a front end housing longitudinally in front of the centralsection; providing a rear end housing longitudinally behind the centralsection; forming the first compartment in the central section; andforming the second compartment partially in the front end housing. Themethod may further include forming the second compartment partially inthe central section below the first compartment. The method in oneexample may further comprise forming one or more hoppers in the centralsection and forming the first compartment at least partially in each ofthe one or more hoppers; extending a portion of each of the one or morehoppers downwardly beyond the part of the second compartment that islocated below the first compartment. The method may further compriseplacing each of the one or more hoppers in fluid communication with adischarge pipe.

In one example the unloading of the first compartment includes opening avalve assembly on each of the one or more hoppers; and allowing the loadin the first compartment to flow from the first compartment into thedischarge pipe under pressure. The method may further comprisemaintaining substantially similar or substantially equal pressure in thefirst and second compartments during unloading; and releasing pressurein the first and second compartments after unloading is completed.

In another aspect, the present disclosure may provide a dry bulk tankfor transporting a load, said tank comprising a tank assembly having afront end and a rear end and defining a longitudinal axis therebetween;a plurality of ground-contacting wheels provided on the tank assembly;more than one sealable area provided in the tank assembly; a system forchanging air pressure; wherein the system is in fluid communication witheach of the more than one sealable area; wherein the system isselectively actuated to substantially equalize air pressure in the morethan one sealable area. A first one of the more than one pressurizedareas comprises a first compartment that is adapted to transport a loadtherein. A second one of the more than one pressurized areas is locatedin abutting contact with the first compartment. In one example thesecond one of the more than one pressurized areas is located forwardlyof the first compartment. In another example, the second one of the morethan one pressurized areas is located beneath the first compartment. Inanother example the second one of the more than one pressurized areas islocated rearwardly of the first compartment. In another example thesecond one of the more than one pressurized areas is partially locatedforwardly of the first compartment; is partially located beneath aportion of the first compartment and is partially located rearwardly ofthe first compartment.

In one embodiment the tank assembly further comprises at least onehopper and wherein an interior compartment is defined in the at leastone hopper and the interior compartment forms a part of the firstcompartment. In one example the at least one hopper may include a firsthopper and a second hopper that are located adjacent each other andwherein a top region of the first hopper is joined to a top region ofthe second hopper; and wherein a portion of an exterior wall of the tankassembly extends between an exterior surface of the first hopper and anexterior surface of the second hopper.

In one example the dry bulk tank further comprises a rib provided insidethe tank assembly; said rib being joined to the top regions of each ofthe first hopper and the second hopper. In one example the tank assemblyis a vessel that is circular in lateral cross-section; and an exteriorcurved surface of the rib is generally U-shaped and is welded to acomplementary interior curved surface of the vessel. The rib defines atleast one aperture therein that extends between a front surface and arear surface of the rib; and wherein a portion of the rib that includesthe aperture is located within one of the more than one sealable area inthe tank assembly. In one example the one of the more than one sealablearea that includes the portion of the rib is located between an exteriorsurface of the first hopper and an exterior surface of the secondhopper.

In one embodiment the system pumps air into the more than one sealablearea. In another embodiment the system pumps air out of the more thanone sealable area. The system includes piping running from an air intakepipe to each of the more than one sealable area. A first section of thepiping terminates in an upper region of one of the more than onesealable area and wherein the one of the more than one sealable area isa first compartment adapted to carry a load therein; and wherein airpressure is applied into the first compartment through the first sectionof piping and from above the load carried in the storage container. Thetank assembly may include at least one hopper extending downwardly froma bottom region of the tank assembly that forms part of the firstcompartment; wherein the at least one hopper defines an exit openingtherein through which the load is removable from the first compartment;and wherein the more than one sealed areas includes a second sealedchamber that at least partially surrounds part of an exterior surface ofthe at least one hopper; and wherein a second section of pipingterminates in the second sealed chamber and wherein air pressure isprovided in the second sealed chamber through the second section of thepiping and pushes upwardly against the air pressure in the at least onehopper.

In one example the system comprises an air intake pipe adapted to beoperatively engaged with a pump; a top air pipe operatively engaged withthe air intake pipe; a first valve operatively engaged with the airintake pipe, the first valve being selectively movable between an openposition and a closed position; and wherein the top air pipe isselectively placeable in fluid communication each of the more than onesealable area when the first valve is in the open position.

In another aspect, the disclosure may provide a dry bulk tank fortransporting a load, said tank comprising a tank assembly having a frontend and a rear end and defining a longitudinal axis therebetween; aplurality of ground-contacting wheels provided on the tank assembly;more than one sealable area defined in the tank assembly; and a systemfor placing all of the more than one sealable area under substantiallysimilar or substantially equal air pressure; and wherein one of the morethan one sealable area is adapted to carry a load therein; and anotherof the more than one sealable area shares a wall in common with the oneof the more than one areas that carries the load. In one example, thesystem pumps air into the more than one sealable area. In anotherexample, the system evacuates air from the more than one sealable area.

In yet another aspect, the disclosure may provide a method of decreasingstress and deformation in a bulk tank trailer comprising forming anexterior wall of the bulk tank trailer into a cylinder; providing one ormore hoppers that each individually extend through a region of a bottomend of the exterior wall; defining a first compartment in an interior ofthe cylinder at the one or more hoppers; defining a sealed compartmentin abutting contact with the first compartment; and applyingsubstantially similar or substantially equal air pressure to the firstcompartment and the sealed compartment. The providing of the one or morehoppers comprises providing a first hopper and a second hopper; and themethod further comprises extending a section of the exterior wall of thecylinder between an exterior surface of the first hopper and an exteriorsurface of the second hopper. In one example, the applying ofsubstantially similar or substantially equal air pressure includespumping air into each of the first compartment and the sealedcompartment. In another example, the applying of substantially similaror substantially equal air pressure includes vacuuming air from each ofthe first compartment and the sealed compartment.

In another aspect, the present invention may provide a method ofminimizing relative movement between component parts of a tank trailercomprising providing a first compartment defined by a first exteriorwall, said first compartment being adapted to retain a load therein;providing a second compartment defined by a second exterior wall;positioning the first compartment adjacent the second compartment suchthat a section of the first exterior wall and a section of the secondexterior wall form a common wall that separates the first and secondcompartments; moving an air pressure in the first compartment and an airpressure in the second compartment in a same direction; and reducingmovement in the common wall as the air pressure in the first compartmentand the air pressure in the second compartment move toward a similarfinal air pressure. The method may further include reducing stress inthe common wall as the air pressure in the first compartment and the airpressure in the second compartment move toward the similar final airpressure. The moving of the air pressure in the first compartment andmoving of the air pressure in the second compartment in the samedirection comprises increasing the air pressure in the first compartmentand increasing the air pressure in the second compartment. The moving ofthe air pressure in the first compartment and moving the air pressure inthe second compartment in the same direction comprises decreasing theair pressure in the first compartment and decreasing the air pressure inthe second compartment. The method may further comprise creating avacuum condition in the first compartment and creating a vacuumcondition in the second compartment. The method may further comprisesubstantially equalizing air pressure in the first compartment and thesecond compartment. The moving of the air pressure in the firstcompartment and the air pressure in the second compartment in the samedirection occurs during loading of the first compartment or duringunloading of the first compartment. The method may further compriseapplying a first force to the common wall with the air pressure in thefirst compartment and applying a second force to the common wall withthe air pressure in the second compartment prior to moving the airpressure in the same direction; wherein the first force and the secondforce are of an unequal magnitude. The first force and the second forceare moved toward a substantially similar or substantially equalmagnitude as the air pressure in the first compartment and the airpressure in the second compartment are moved toward in the samedirection. The method may further comprise moving a portion of thecommon wall outwardly away from the first compartment or moving aportion of the common wall inwardly toward the first compartment priorto moving the air pressure in the first compartment and the air pressurein the second compartment in the same direction. The method may furthercomprise reducing a degree of motion of the portion of the common wallas the air pressure in the first compartment and the air pressure in thesecond compartment are moved in the same direction. The moving of theair pressure in the first compartment and the air pressure in the secondcompartment in the same direction comprises placing the firstcompartment and the second compartment in fluid communication. Theplacing of the first and second compartments in fluid communicationincludes providing a pipe that has a first end in the first compartmentand a second end in the second compartment. The method may compriseestablishing atmospheric pressure in the first compartment and in thesecond compartment or evacuating air from the first compartment and thesecond compartment.

In yet another aspect, the invention may provide a method of loading andunloading a dry bulk tank comprising providing a tank assembly defininga first compartment for carrying a load and a second compartment locatedvertically beneath at least a portion of the first compartment and inabutting contact with the first compartment; placing the firstcompartment and second compartment in fluid communication with a devicefor pressurizing air in the first and second compartments or with adevice for creating a vacuum in the first and second compartments. Themethod may further comprise placing the first compartment in fluidcommunication with the second compartment utilizing an air pipingsystem. The method may further comprise operatively engaging at leastone valve with the air piping system; moving the at least one valve froma first position to a second position to place the first and secondcompartments under vacuum and moving the at least one valve from thesecond position to the first position to pressurize the first and secondcompartments. The method may further comprise automatically moving theat least one valve between the first and second positions. The moving ofthe at least one valve between the first and second positions includesutilizing an operator located on the ground alongside the tank assembly.The method may include creating a vacuum in the first and secondcompartment without the operator moving hoses between a front end and aback end of the tank assembly.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

A sample embodiment of the disclosure is set forth in the followingdescription, is shown in the drawings and is particularly and distinctlypointed out and set forth in the appended claims. The accompanyingdrawings, which are fully incorporated herein and constitute a part ofthe specification, illustrate various examples, methods, and otherexample embodiments of various aspects of the disclosure. It will beappreciated that the illustrated element boundaries (e.g., boxes, groupsof boxes, or other shapes) in the figures represent one example of theboundaries. One of ordinary skill in the art will appreciate that insome examples one element may be designed as multiple elements or thatmultiple elements may be designed as one element. In some examples, anelement shown as an internal component of another element may beimplemented as an external component and vice versa. Furthermore,elements may not be drawn to scale.

FIG. 1 is a side elevation view of a PRIOR ART dry bulk tank;

FIG. 2 is a longitudinal cross-section of the PRIOR ART dry bulk tanktaken along line 2-2 of FIG. 1 and with several components omitted forclarity of illustration;

FIG. 2A is a longitudinal cross-section of the PRIOR ART dry bulk tanktaken along line 2-2 of FIG. 1 and with several components omitted forclarity of illustration; and showing the bulk material carrying regionof the tank trailer;

FIG. 3 is a lateral cross-section of the PRIOR ART dry bulk tank takenalong line 3-3 of FIG. 1 with several components omitted for clarity ofillustration; and

FIG. 4 is a lateral cross-section of the PRIOR ART dry bulk tank takenalong line 4-4 of FIG. 1 with several components omitted for clarity ofillustration;

FIG. 5 is a side elevational view of a dry bulk tank in accordance withthe present disclosure;

FIG. 6 is a longitudinal cross-section taken along line 6-6 of FIG. 5and showing the openings for piping used to pressurize the front endhousing and bulk material carrying region;

FIG. 6A is a longitudinal cross-section of the dry bulk tank showing thepressurization of the front end housing and bulk material carryingregion and the flow of air from the pressurized front end housingthrough the lower chamber to the rear end housing;

FIG. 7 is a lateral cross-section of the dry bulk tank taken along line7-7 of FIG. 6;

FIG. 7A is an enlargement of the highlighted region of FIG. 7;

FIG. 8 is a lateral cross-section of the dry bulk tank taken along line8-8 of FIG. 6;

FIG. 9 is a front elevation view of the dry bulk tank of FIG. 5;

FIG. 10 is executed in color and shows an ANSYS® Deformation Analysis ofa PRIOR ART dry bulk tank (ANSYS® is a registered trademark of Ansys,Inc. of Canonsburg, Pa., USA);

FIG. 11 is executed in color and shows an ANSYS® Deformation Analysis ofthe dry bulk tank in accordance with the present disclosure;

FIG. 12 is executed in color shows an ANSYS® Stress Analysis of a PRIORART dry bulk tank;

FIG. 13 is executed in color shows an ANSYS® Stress Analysis of the drybulk tank in accordance with the present disclosure;

FIG. 14 is a side elevation view of a dry bulk tank in accordance withthe present disclosure and having an air piping system that includes asystem for pressurizing the tank and a system for generating a vacuumwithin the tank;

FIG. 15 is a longitudinal cross-section of the dry bulk tank of FIG. 14with the shrouds above the two wheel assemblies removed so that the endsof the exhaust pipe and intake pipe may be seen;

FIG. 16A is an enlarged side elevation of the front end of the dry bulktank of FIG. 14 showing air flow through the air piping system when thetank is placed under vacuum;

FIG. 16B is an enlarged side elevation of the rear end of the dry bulktank of FIG. 14 showing air flow through the back end of the dry bulktank when the tank is placed under vacuum.

FIG. 17A is an enlarged side elevation of the front end of the dry bulktank of FIG. 14 showing the air flow through the front end of the drybulk tank when the tank is pressurized;

FIG. 17B is an enlarged front elevation of the dry bulk tank of FIG. 14showing the air flow through the front end of the dry bulk tank when thetank is pressurized;

FIG. 17C is an enlarged rear elevation view of the dry bulk tank of FIG.14; and

FIG. 18 is an enlarged side elevation of the front end of the dry bulktank of FIG. 14 showing the air flow through the front end of the drybulk tank when the tank is depressurized.

Similar numbers refer to similar parts throughout the drawings.

DETAILED DESCRIPTION

FIGS. 1-4 show a PRIOR ART bulk tank trailer and FIGS. 5-9 show a firstembodiment of a bulk tank trailer in accordance with the presentdisclosure. FIGS. 10 and 11 show a second embodiment of a bulk tanktrailer in accordance with the present disclosure.

The term “trailer” will be used throughout the rest of the specificationto reference either of the PRIOR ART bulk tank trailer or the bulk tanktrailer in accordance with the present disclosure. However, it should beunderstood that the terms “trailer”, “bulk tank trailer”, “tanker”,“tank”, “truck”, or “vehicle” may be used interchangeably herein.

Referring to FIGS. 1-4, the PRIOR ART bulk tank trailer will bedescribed in greater detail and is generally indicated in these figuresby the reference number 10. Bulk tank trailer 10 may be similarlyconfigured to a bulk tank trailer described in U.S. patent applicationSer. No. 15/056,496 filed Feb. 29, 2016 and assigned to the sameApplicant as the present disclosure. U.S. patent application Ser. No.15/056,496 is entitled “Pneumatic Tank with Tension Bar”, and thedisclosure of this application is incorporated herein by reference.

Trailer 10 may be a towed vehicle which is towed by a towing vehiclesuch as an on-road tractor (not shown) whereby trailer 10 and thetractor may form a tractor trailer rig in the form of a dry bulk tankerto transport dry particulate or granular materials. Trailer 10 may havea front end 10 a and a rear end 10 b defining between them alongitudinal direction. Front end may be pivotally hitched to a rear endof tractor via a hitch member 12. Hitch member 12 may be any suitabletype of hitch such as a fifth wheel hitch. Trailer 10 further includes atop 10 c, a bottom 10 d, a left side 10 e and a right side 10 f (FIG.3). Top 10 c and bottom 10 d define a vertical direction therebetweenand left and right sides 10 e, 10 f define a lateral directiontherebetween.

For clarity, an explanation of some terms used herein is provided.Trailer 10 may have an imaginary axial center plane CP (FIGS. 3 and 4)which may be a vertical longitudinally extending plane cutting throughthe center of trailer 10 midway between the left and right sides 10 eand 10 f thereof. As is readily evident from the Figures, variouscomponents may be axially offset or spaced from center plane CP. Thedescription of trailer 10 may make reference to certain components,sides, surfaces, points and the like as being inboard or outboard of oneanother, or this may be readily apparent from the Figures even withoutspecific description. Such terms typically relate to the left or righthalves of trailer 10 whereby, for instance, with regard to the left half(left of central plane CP), a first point which is outboard of a secondpoint is further to the left than the second point or further outboardthan the second point in a first or left outboard direction, and thusthe second point is inboard of or to the right of the first point. Thus,within the left half, the first point is further outboard or furtherfrom center plane CP than is the second point. Likewise, with regard tothe right half (right of central plane CP), a third point which isoutboard of a fourth point is further to the right than the fourth pointor further outboard than the fourth point in a second or right outboarddirection, and thus the fourth point is inboard of or to the left of thethird point. Thus, within the right half, the third point is furtheroutboard or further from center plane CP than is the fourth point.

Various surfaces may be said to face axially inward or axially outward,which may respectively mean facing generally toward or away from theimaginary center plane CP. Thus, on the left half of trailer 10, asurface which faces axially inward may be said to face generally to theright or rightward, and a surface which faces axially outward may besaid to face generally to the left or leftward. On the right half oftrailer 10, a surface which faces axially inward may be said to facegenerally to the left or leftward, and a surface which faces axiallyoutward may be said to face generally to the right or rightward.

Similarly, various components, surfaces etc. may be said to extendaxially inward or axially outward, which may respectively mean extendinggenerally toward or away from center plane CP. Thus, on the left half oftrailer 10, a component that extends axially inward may be said toextend generally to the right or rightward, and a component that extendsaxially outward may be said to extend generally to the left or leftward.On the right half of trailer 10, a component that extends axially inwardmay be said to extend generally to the left or leftward, and a componentetc. which extends axially outward may be said to extend generally tothe right or rightward.

Further explanation is provided with respect to references to thelongitudinal direction of trailer 10. Certain components of trailer 10are further forward or rearward of other components, or may be at thesame location along a longitudinal axis (where the longitudinal axisextends between front end 10 a and rear end 10 b. Thus, for example, areference to two points, surfaces, components or the like being “at thesame longitudinal position” or “at the same longitudinal location” meansthat the two points, surfaces, components or the like are at the sameposition along the longitudinal axis while they may be at differentaxial positions, that is, spaced to the left or right of one another, orspaced upwardly or downwardly of one another. Similarly, a reference totwo points, surfaces, components or the like being “longitudinallyadjacent” one another means that the two points, surfaces, components orthe like are at or adjacent the same position along the longitudinalaxis while they may be at different axial positions or spaced upwardlyor downwardly of one another. It is also noted that the term U-shaped orU-shaped configuration may be used herein to mean an upright U-shape orU-shaped configuration and the term inverted U-shaped configuration maybe used herein to mean an upside down U-shaped configuration.

With primary reference to FIGS. 1 and 2, trailer 10 comprises a rigidtank assembly 14 that includes a front end housing 16, a central section18, and a rear end housing 20. Front end housing 16 extends forwardlyfrom the central section 18 and rear end housing 20 extends rearwardlyfrom the central section 18. Front end housing 16, central section 18and rear end housing 20 are formed from a plurality of differentlyshaped sheet metal sections that are welded together to form theillustrated exterior shape of tank assembly 14.

Front end housing 16 forms a nose cone on tank assembly 14. Housing 16includes an exterior wall 16 a that bounds and defines an interior frontchamber 16 b. Wall 16 a defines one or more openings 16 c that placeinterior front chamber 16 b in fluid communication with the air thatsurrounds tank assembly 14. Front end housing 16 also includes one ormore support walls 16 d therein that provide strength and rigidity tofront end housing 16. Support wall 16 d as illustrated in FIG. 2 mayalso define an opening 16 e therein that allows air to flow betweendifferent interior sections of front end housing 16 that are divided bysupport wall 16 d. Air from outside tank assembly 14 may thereforefreely circulate into, around and out of inter front chamber 16 b.Exterior wall 16 a defines an inlet 16 f therein, the purpose of whichwill be described later herein.

Central section 18 includes an inverted, generally U-shaped upper wall18 a. The inverted generally U-shaped upper wall 18 a gives the tankassembly 14 a generally ovoid or elliptical shape when tank assembly 14viewed in cross-section as in FIGS. 3 and 4. Upper wall 18 a bounds anddefines a generally U-shaped interior space 18 b (when viewed incross-section from a front or rear end of trailer 10). An inlet 18 c isdefined in upper wall 18 a in a top region proximate the top 10 c oftrailer 10. The top region of upper wall 18 a also defines one or moremanhole openings 18 d therein. Inlet 18 c and manhole openings 18 d arein fluid communication with interior space 18 b. Manholes 18 e extendupwardly and outwardly from the top region of upper wall 18 a and covers18 f are selectively engageable with manholes 18 e. When covers 18 f areremoved then the manhole openings 18 d and thereby interior space 18 bare in fluid communication with the air surrounding trailer 10. Whencovers 18 f are engaged on manholes 18 e then interior space 18 b is nolonger in fluid communication with the air surrounding trailer 10. Inthe figures, inlet 18 c is shown located forwardly of the forwardmostmanhole 18 e but it will be understood the inlet 18 c may be provided inany suitable location on upper wall 18 a. The purpose of inlet 18 c willbe described later herein.

Rear end housing 20 extends longitudinally rearwardly from centralsection 18. Rear end housing 20 has an exterior wall 20 a that boundsand defines an interior space 20 b. One or more openings 20 c may bedefined in exterior wall 20 a and as a result air within interior space20 b is in fluid communication with the air surrounding tank assembly14. One or more vertical support walls 20 d extends from a top region ofrear end housing 20 to a bottom region thereof. Support wall 20 d maydefine one or more openings 20 e therein so that the air in a firstsection of interior space 20 b and a second section of interior space 20b can mix with the air outside tank assembly 14.

One or more hoppers are welded to and extend downwardly from a lower endof upper wall 18 a of central section 18. Trailer 10 may be configuredwith one, two, three, or more than three hoppers. As illustrated inFIGS. 1-4, trailer 10 includes a first hopper 22, a second hopper 24,and a third hopper 26. Center plane CP may cut through the axial centerof each of hoppers midway between the left and right sides of trailer10. First hopper 22 may be located closest to front end housing 16,second hopper 24 may be located longitudinally rearwardly of firsthopper 22 and generally centrally relative to central section 18, andthird hopper 26 may be located longitudinally rearwardly of secondhopper 24 and closest to rear end housing 20. First, second and thirdhoppers 22, 24, 26 may be generally aligned along a longitudinal axis oftank assembly 14, where the longitudinal axis is aligned along centralplane “CP” and extends from front end 10 a to rear end 10 b of trailer10. Each hopper 22, 24, 26 may be formed with a truncated generallyconical exterior wall that tapers in width from the lower end of upperwall 18 a towards a bottom 10 d of trailer 10. The term “conical” asused herein should be understood to describe a hopper that has acircumferential surface that is curved or that is partially comprised ofcurved surface and partially comprised of flat surfaces or that isentirely comprised of flat surfaces that are oriented at angles to eachother. Hoppers 22, 24, 26 will be further described later herein.

As best seen in FIGS. 2 and 2A the conical exterior wall of first hopperincludes a front region 22 a and an opposed rear region 22 b. An opening22 c is defined at a bottom end of the conical exterior wall. Theconical exterior wall of first hopper 22 bounds and defines an interiorspace 22 d and opening 22 c is in fluid communication with interiorspace 22 d. As illustrated in FIGS. 2 and 2A opening 22 c is also influid communication with the air surrounding trailer 10 although a valveassembly 34 (FIG. 1) is typically provided at the bottom end of firsthopper 22 to close off access to interior space 22 d. Front region 22 aof the conical exterior wall of first hopper 22 angles forwardly andupwardly and is welded at its uppermost end to an interior surface ofthe top region of upper wall 18 a. The front region 22 a forms arearmost wall of front end housing 16.

Referring still to FIGS. 2 and 2A, the conical exterior wall of secondhopper 24 includes a front region 24 a and a rear region 24 b and anopening 24 c is defined in the bottom end of the conical wall. Theconical exterior wall of second hopper 24 bounds and defines an interiorspace 24 d and opening 24 c is in fluid communication with interiorspace 24 d. As illustrated in these figures interior space 24 d is alsoin fluid communication with the air surrounding trailer 10 although avalve assembly 34 (FIG. 1) is typically provided at the bottom end ofsecond hopper 24 to close off access to interior space 24 d.

An upper end of rear region 22 b of first hopper 22 and an upper end offront region 24 a of second hopper 24 may be welded to each other and toa first plate 28. First plate 28 extends transversely across theinterior of tank assembly 14. The ends of first plate 28 are welded toopposing regions of the interior surface of upper wall 18 a. First plate28 may be of a substantially constant height from an upper end 28 athereof to a lower end 28 b thereof. First plate 28 may comprise asubstantially solid and substantially uninterrupted piece of metal(i.e., substantially no holes, openings or slots being defined therein).

The conical exterior wall of third hopper 26 includes a front region 26a and a rear region 26 b. An opening 26 c is defined in the bottom endof the conical wall. The conical exterior wall of third hopper 26 boundsand defines an interior space 26 d and opening 26 c is in fluidcommunication with interior space 26 d. As illustrated in FIGS. 2 and 2Aopening 26 c is also in fluid communication with the air surroundingtrailer 10 although a valve assembly 34 (FIG. 1) is typically providedat the bottom end of third hopper 26 to close off access to interiorspace 26 d.

An upper end of rear region 24 b of second hopper 24 and an upper end offront region 26 a of third hopper 26 may be welded to each other and toa second plate 30. Second plate 30 may be of a substantially identicalconfiguration to first plate 28 and second plate 30 extends transverselyacross the interior of tank assembly 14 and the ends of second plate 30are welded to opposing regions of the interior surface of upper wall 18a. Second plate 30 may be of a substantially constant height from anupper end 30 a thereof to a lower end 30 b thereof. Second plate 30 maycomprise a substantially solid and substantially uninterrupted piece ofmetal (i.e., substantially no holes, openings or slots being definedtherein). First plate 28 and second plate 30 may be substantiallyparallel to each other and at right angles to the longitudinal axis oftrailer 10. First plate 28 and second plate 30 are also longitudinallyspaced a distance apart from each other. Most of first plate 28 and mostof second plate 30 is located within the interior of tank assembly 14.However, a portion of first plate 28 projects downwardly from thejunction between rear region 22 b of first hopper 22 and front region 24a of second hopper 24 and a portion of second plate 30 projectsdownwardly from the junction between rear region 24 b of second hopper24 and front region 26 a of third hopper 26. This can be seen in FIGS. 1and 2A.

Rear region 26 b of third hopper 26 extends upwardly and rearwardly fromthe bottom 10 d of trailer 10 to the interior surface of a top region ofupper wall 18. Rear region 26 b is welded to the interior surface ofupper wall 18 and forms a rearmost wall of central section 18 and afrontmost wall of rear end housing 20.

Interior space 18 b defined by upper wall 18 a, interior space 22 ddefined by first hopper 22, interior space 24 d defined by second hopper24 and interior space 26 d defined by third hopper 26 form a storagecompartment 32 for tank assembly 14. Storage compartment 32 is suitablefor carrying dry bulk materials therein. The one or more manholes 18 eprovide a way for dry bulk materials to be loaded into storagecompartment 32 and the openings 22 c, 24 c, 24 d provide a way for thosedry bulk materials to be removed from storage compartment 32.

As is evident from FIG. 2A chamber 16 b of front end housing 16 iscompletely separate from storage compartment 32. Furthermore, chamber 20b of rear end housing 16 is completely separate from storage compartment32. Both of chamber 16 b and chamber 20 b are open to the airsurrounding tank assembly 14. Storage compartment 32, on the other hand,is able to be sealed from contact with the air surrounding tank assembly14 by covers 18 f being engaged on manholes 18 e and by valve assemblies34 (FIG. 1) that are engaged with hoppers 22, 24, 26. Each valveassembly 34 is individually movable between an open position and aclosed position. For example, with respect to first hopper 22, when theassociated valve assembly 34 is moved to the open position, bulkmaterial from interior space 22 d of first hopper 22 is able to flowthrough opening 22 c. When the associated valve assembly 34 is closed,bulk material can no longer flow out of opening 22 c. An aerator 36 isalso engaged with each the bottom end of each hopper 22, 24, 26. Theaerators 36 are provided to selectively agitate the bulk materialsstored in the associated hopper. The aerator 36 on a particular hopper,such as first hopper 22, will be actuated prior to opening theassociated valve assembly 34. The aerator 36 will stir up theparticulate materials within first hopper 22 and effectively fluidizethem, thereby making it easier for the particulate materials to flow outthrough opening 22 c when the associated valve assembly 34 is moved tothe open position.

As shown in FIGS. 1 and 3, a strengthening assembly 38 is welded to theexterior surface of central section 18. Assembly 38 includes a pluralityof inverted U-shaped ribs 38 a, 38 b, 38 c, and 38 d; a pair ofhorizontally oriented bars 38 e and 38 f (FIG. 3), and a plurality ofgusset plates 38 g. Typically, four generally triangular gusset plates38 g will be provided as part of strengthening assembly 38 with eachgusset plate 38 g being located where two adjacent hoppers are connectedto each other. Gusset plates 38 g also strengthen the area of theexterior of tank assembly 14 where the first and second plates 28, 30are welded to upper wall 18 a and the front and rear regions of theadjacent hoppers 22, 24 or 26.

Ribs 38 a, 38 b, 38 c and 38 d are welded to the exterior surface ofupper wall 18 a and are spaced at intervals longitudinally from eachother. Ribs 38 a-38 d may be oriented at right angles to thelongitudinal axis. Bars 38 e, 38 f are located on opposite sides 10 e,10 f of trailer 10 and are welded to upper wall 18 a, to ribs 38 a-38 dand to gusset plates 38 g. As indicated above, each gusset plate 38 g islocated at the intersection of two adjacent hoppers, such as firsthopper 22 and second hopper 24 or second hopper 24 and third hopper 26.Gusset plates 38 g are welded to upper wall 18 a, one of the ribs 38 bor 38 c and portions of the adjacent hoppers conical exterior walls.Each gusset plate 38 g may be positioned exteriorly of the locationwhere an end of first plate 28 or second plate 30 is welded to the upperwall 18 a and associated hopper conical exterior walls. Strengtheningassembly 38 is provided to help the exterior wall of tank assembly 14withstand the stresses and strains placed on it during transportation ofa load and during loading and unloading of the storage compartment 32.

Front end housing 16, central section 18, rear end housing 20, hoppers22, 24, 26, strengthening assembly 38 amongst other components on tankassembly 14 may be formed primarily of a metal, for instance, analuminum alloy or any other suitable metal.

Left and right sets of ground engaging wheels 40 may be rotatablymounted on tank assembly 14 about respective horizontal axiallyextending axles and via a suitable suspension assembly 42 which may besecured to rear end housing 20 and extend downwardly therefrom adjacentrear end 10 b of trailer 10. Trailer 10 may include landing gear 44generally adjacent front end 10 a. Landing gear 44 may be any suitabletype known in the art and may be configured to move between a loweredposition (FIG. 1) in contact with the ground “G” for supporting frontend 10 a of trailer 10 when disconnected from the tractor or othertowing vehicle; and a raised position (not shown) out of contact withthe ground “G” when trailer 10 is hitched to the tractor/towing vehiclefor over the road travel.

Tank assembly 14 may include a front frame 46, which may be referred toas a hitch mounting frame (for mounting hitch member 12 thereon), alanding gear mounting frame (for mounting landing gear 44 thereon) or ahitch and landing gear mounting frame (for mounting hitch member 12 andlanding gear 44 thereon). Front frame 46 may be a rigid structure andmay be formed primarily of an aluminum alloy or other suitable metal.Front frame 46 may be rigidly secured to and extend downward from alower portion of front end housing 16 and front region 22 a of firsthopper 22. Tank assembly 14 and suspension assembly 42 may include arear/suspension frame 48, which may be referred to as a wheel mountingframe on which wheels 40 are rotatably mounted. Rear suspension frame 48may be a rigid structure and may be formed primarily of an aluminumalloy or other suitable metal. Rear suspension frame 48 may be rigidlysecured to and extend downward from a lower portion of rear end housing20 and a lower rear region 26 b of third hopper 26.

An air piping system 50 is provided on trailer 10. Air piping system isprovided to aid in the removal of the bulk load carried within storagecompartment 32 of tank assembly 14. Air piping system 50 includes aplurality of different pipes, hoses, lines and valves (as will bediscussed hereafter). Assembly 50 may be connected to an air/pneumaticpump or compressor (not shown) which may be mounted on the towingvehicle or tractor or elsewhere. The pump typically will be locatedupstream of air piping system 50 and storage compartment 32.

Air piping system 50 includes an air intake pipe 52 that may beselectively placed in fluid communication with the upstream pump. A hose(not shown) may be engaged with the pump at one end and with a first end52 a of air intake pipe 52 at the other end. A top air pipe 54 branchesoff air intake pipe 52 and a first valve 56 is engaged with top air pipe54. Top air pipe 54 terminates in a blowdown pipe 58 and is in fluidcommunication therewith. A first branch 58 a of blowdown pipe 58 extendsupwardly from top air pipe 54 and first branch 58 a terminates in theinterior of storage compartment 32. First branch 58 a of blowdown pipe58 enters tank assembly 14 through inlet 18 c (FIG. 2) defined incentral section 18. A second branch 58 b of blowdown pipe 58 entersfront end housing 16 through inlet 16 f and subsequently exits front endhousing 16 through one of the openings 16 c in a lower wall of front endhousing 16. Second branch 58 b terminates at an open end 58 c (FIG. 2).A second valve 60 is engaged with second branch 58 b of blowdown pipe58.

First and second valves 56 and 60 may each be selectively andindividually moved between an open position and a closed position. Whenfirst valve 56 is in the open position and second valve 60 is in theclosed position, air may flow from air intake pipe 52, through top airpipe 54, through first branch 58 a of blowdown pipe 58 and into storagecompartment 32. The pump may be activated to pressurize storagecompartment 32 by pumping air through top air pipe 54 and the firstbranch 58 a of blowdown pipe 58 and into the interior of storagecompartment 32. Storage compartment 32 is pressurized from the top topush particulate material out of the openings in the bottom end of thehoppers as will be discussed later herein. Air is pumped into storagecompartment 32 until the pressure is in the range of about 10-15 Psi.The cross-hatching used in FIG. 2A indicates the parts of tank assembly14 that are pressurized in this manner. As is evident from FIG. 2, onlystorage compartment 32 is pressurized. Front end housing 16 and rear endhousing 20 are open to the atmosphere because of the openings 16 c and20 c respectively. Both of front end housing 16 and rear end housing 20are therefore under atmospheric pressure. There is therefore a pressuredifferential across all of the walls that define and bound storagecompartment 32. That pressure differential is the difference betweenatmospheric pressure outside of storage compartment 32 and the increasedpressure inside storage compartment 32.

When first valve 56 is moved to the closed position, air no longer canflow through top air pipe 54, through first branch 58 a of blowdown pipe58 and into storage compartment 32. When first valve 56 is in the closedposition and second valve 60 is also in the closed position, airpressure within storage compartment 32 remains substantially constant.If it is desired to depressurize storage compartment 32, first valve 56is maintained in the closed position and second valve 60 is moved to theopen position. This allows air to flow out of storage compartment 32,through first branch 58 a of blowdown pipe 58, through second branch 58b of blowdown pipe 58 and out of the open end 58 c thereof and into theair below tank assembly 14.

Referring still to FIG. 1, air piping system 50 further includes anaerator supply pipe 62 that originates at 62 a in air intake pipe 52 andconnects to aerators 36 engaged with the bottom ends of each of thefirst, second and third hoppers 22, 24, 26 and terminates in an end 62b. When one of the aerators 36 is activated, air will flow throughaerator supply pipe 62 and into the chamber of the associated hopper 22,24 or 26 to stir up the bulk material in the chamber. This helps tofluidize the bulk material so that is more readily able to flow out ofan opening at the bottom of the associated hopper 22, 24 or 26.

Air piping system 50 further includes a discharge pipe 64 thatoriginates in air intake pipe 52. A discharge valve 66 is engaged withair intake pipe 52 proximate a first end 64 a thereof and dischargevalve 66 is movable between an open position and a closed position.Discharge pipe 64 is also engaged with the valve assemblies 34 locatedat the bottom end of each of the first, second and third hoppers 22, 24,and 26. Each valve assembly 34 is selectively movable between an openposition and a closed position. Discharge pipe 64 terminates in an openend 64 b that is located at a rear end 10 b of trailer 10. When one ofthe valve assemblies 34 is moved to the open position, the chamber ofthe associated hopper 22, 24 or 26, and thereby storage compartment 32,is placed in fluid communication with discharge pipe 64. When the valveassembly 34 is moved to the closed position then fluid communicationbetween discharge pipe 64 and the chamber of the associated hopper 22,24 or 26 and thereby with storage compartment 32 is broken.

When discharge valve 66 is in the open position, discharge pipe 64 isplaced in fluid communication with air intake pipe 52 and air may flowfrom the pump through air intake pipe 54 and through discharge pipe 64under pressure. If the valve assembly 34 associated with first hopper22, for example, is moved to the open position, bulk material will flowout of the storage compartment 32 through the valve assembly 34 of firsthopper 22 and into discharge pipe 64. The pressurized air flowingthrough discharge pipe 64 will entrain some of the bulk material andcause the bulk material to flow through discharge pipe 64 and out ofopen end 64 b.

PRIOR ART trailer 10 is used in the following manner. When trailer 10arrives at a facility to be loaded with particulate bulk material,trailer 10 is positioned so that at least one of manholes 18 e islocated directly under an opening of a loading hose or pipe. Cover 18 fof the at least manhole 18 e is removed and dry, particulate, bulkmaterial is loaded into storage compartment 32 through the at least onemanhole 18 e. Cover 18 f is then replaced on each of the at least onemanhole 18 e to seal storage compartment 32. Trailer 10 is then drivenacross the roads to a second facility where the bulk particulatematerial is to be delivered.

The operator will connect a hose from a storage bin at the secondfacility to end 64 b of discharge pipe 64. Discharge valve 66 is movedto the closed position if it is not already in that position. First andsecond valves 56 and 60 are also placed in the closed position if theywere not already in that position. A hose is connected from a pump tofirst end 52 a of air intake pipe 52 and the pump is actuated. Air flowsthrough air intake pipe 52 and because discharge valve 66 is closed, theair will flow through aerator supply pipe 62. In one example method, afirst one of the aerators 36 is activated to agitate the particulatematerial within the associated hopper 22, 24 or 26. Air will thereforeflow from air intake pipe 52 through the activated aerator 36 and intothe chamber of the associated hopper 22, 24 or 26. When the aerator 36has been running for a few minutes, discharge valve 66 is moved to theopen position and the valve assembly 34 on the hopper 22, 24 or 26 thathas been aerated will be moved to the open position. (The aerator 36will be deactivated prior to or after the valve assembly 34 on thathopper has been moved to the open position.) The first valve 56 may alsobe moved to the open position so that air flows in to the upper end ofstorage compartment 32 to pressurize storage compartment 32. The bulkmaterial in the opened hopper 22, 24 or 26 flows out through the openedvalve assembly 34 and into the discharge pipe 64. The air flowingthrough discharge pipe 64 picks up the bulk material from the hopper andcarries it through the discharge pipe 64, out of the open end 64 b, andinto and through the hose connected to the storage tank in the secondfacility.

When substantially all of the loose material in the opened hopper hasflowed into the discharge pipe 64 the valve assembly 34 associated withthat opened hopper will be closed as will the discharge valve 66. Theaerator 36 engaged with another one of the hoppers will be activated andthe process will be repeated until that hopper is substantially emptied.The steps will be repeated once again for the final hopper. Whensubstantially all of the bulk material has been removed from the storagecompartment 32 through the three hoppers 22, 24, 26, discharge valve 66will be kept in the open position so that air continues to flow throughdischarge pipe 64. The operator will leave first valve 56 in the openposition for a while to ensure that air continues to be moved from airintake pipe 52 through top air pipe 54, through blowdown pipe 58 andinto storage compartment 32. The air flowing into storage compartment 32through blowdown pipe 58 will help dislodge any material that remains inany of the hoppers 22, 24, 26. That dislodged material will flow intothe discharge pipe 64 and through open end 64 b thereof and into thehose connected to end 64 b.

First valve 56 will then be closed and second valve 60 will be opened todepressurize storage compartment 32. The pump will be switched off, allvalves 56, 60 and 66 will be closed and the hoses engaged with first end52 a of air intake pipe 52 and with end 64 b of discharge pipe 64 willbe disengaged. Trailer 10 is then free to travel back to the loadingfacility to take on its next load.

It will be understood that in other example methods of emptying a loadfrom trailer 10, more than one of the aerators and more than one of thehoppers may be opened at the same time instead of opening the aeratorsand hoppers in sequence one at a time. In some example methods, therearmost hopper (i.e., hopper 26 in the PRIOR ART figures) may be openedfirst and then the middle hopper (second hopper 24) and then the firsthopper 22. In other example methods, the hoppers may be opened in theopposite sequence starting with the first hopper 22, then the secondhopper 24 and finally the third hopper 26.

One of the issues with PRIOR ART tank trailers such as bulk tank trailer10 is that the regions of the trailer where the hoppers 22, 24, 26 jointhe upper wall 18 and where adjacent hoppers are joined to each othertend to experience high stress when the storage compartment 32 ispressurized. This is particularly true because trailer 10 is generallyelliptical in shape (or generally ovoid) as can be seen in FIGS. 3 and4. The stresses are particularly high where the conical wall of eachhopper 22, 24, 26 joins the upper wall 18. The regions where the conicalwall of each hopper 22, 24, 26 joins upper wall 18 a may experiencepressures in the range of about 15 Psi because of the internal pressurein storage compartment 32. Still further, there may be quite a lot ofrelative movement between the generally elliptical upper wall 18 and thehoppers 22, 24, 26 and the ribs 38. In order to help tank assembly 14 towithstand these stresses due to pressure and to stabilize the componentparts of the trailer against too much relative movement, strengtheningassembly 38 is provided. Ribs 38 a-38 d, bars 38 e, 38 f, plates 38 gand first and second plates 28, 30 and the relatively thick exteriorwall are provided to ensure tank assembly 14 can withstand thepressurization of storage compartment 32.

FIGS. 5-9 illustrate a tank trailer in accordance with the presentinvention, generally indicated at 100. Trailer 100 is similar to thePRIOR ART trailer 10 in some respects but is also very different inother respects. The differences between the PRIOR ART trailer 10 andtrailer 100 will be described in detail hereafter.

Trailer 100 has a front end 100 a, a rear end 100 b, a top end 100 c, abottom end 100 d, a left side 100 e (FIG. 7) and a right side 100 f.Trailer 100 like PRIOR ART trailer 10 comprises a tank assembly 102 thatincludes a front end housing 104, a central section 106 and a rear endhousing 108. However, as is most evident when comparing FIGS. 3 and 7,trailer 100 is generally circular in lateral cross-section while PRIORART trailer 10 is generally elliptical or ovoid in lateralcross-section. As illustrated in FIG. 5, trailer 100 may be mounted on aframe that includes left and right sets of ground engaging wheelssimilar to wheels 40. The wheels are mounted to a frame of tank assembly102 and are rotatable about respective horizontally extending axles. Thewheels are engaged to the frame via a suitable suspension assembly(similar to suspension 42) that may be secured to rear end housing 108and extend downwardly therefrom adjacent rear end 100 b of trailer 100.Trailer 100 may include landing gear (similar to landing gear 44)generally adjacent front end 100 a. The landing gear may be any suitabletype known in the art and may be configured to move between a loweredposition (FIG. 5) in contact with the ground for supporting front end100 a of trailer 100 when disconnected from the tractor or other towingvehicle; and a raised position (not shown) out of contact with theground when trailer 100 is hitched to the tractor/towing vehicle forover the road travel.

Front end housing 104 is located proximate front end 100 a of trailer,central section 106 extends longitudinally rearwardly from front endhousing 104 and rear end housing 108 extends longitudinally rearwardlyfrom central section 106. Front end housing 104, central section 106 andrear end housing 108 are aligned along a longitudinal axis of trailer100. A rib assembly is welded to an exterior surface of central section106. The rib assembly 107 includes a plurality of ribs 107 a, 107 b, 107c, 107 d that are spaced at intervals longitudinally from each otheralong central section 106. The ribs 107 a, 107 b, 107 c, 107 d may besubstantially parallel to each other. Some or all of ribs 107 a-107 dmay be circumferential in nature and may circumscribe substantially theentire circumference of central section 106. Others of ribs 107 a-107 dmay not extend the entire way around the circumference of centralsection 106. Ribs 107 a-107 d are oriented at right angles to thelongitudinal axis of tank assembly 102 (where the longitudinal axisextends between front end 100 a and rear end 100 b). Ribs 107 a-107 dare provided to strengthen central section 106.

Trailer 100 may have an imaginary axial center plane CP (FIGS. 7 and 8)which may be a vertical longitudinally extending plane cutting throughthe center of trailer 100 midway between the left and right sides 100 eand 100 f thereof. The circumferential ribs of rib assembly 107 areoriented at right angles to the longitudinal plane. As is readilyevident from the Figures, various components may be axially offset orspaced from center plane CP. The description of trailer 100 may makereference to certain components, sides, surfaces, points and the like asbeing inboard or outboard of one another, or this may be readilyapparent from the Figures even without specific description. Such termstypically relate to the left or right halves of trailer 100 whereby, forinstance, with regard to the left half (left of central plane CP), afirst point which is outboard of a second point is further to the leftthan the second point or further outboard than the second point in afirst or left outboard direction, and thus the second point is inboardof or to the right of the first point. Thus, within the left half, thefirst point is further outboard or further from center plane CP than isthe second point. Likewise, with regard to the right half (right ofcentral plane CP), a third point which is outboard of a fourth point isfurther to the right than the fourth point or further outboard than thefourth point in a second or right outboard direction, and thus thefourth point is inboard of or to the left of the third point. Thus,within the right half, the third point is further outboard or furtherfrom center plane CP than is the fourth point.

Various surfaces may be said to face axially inward or axially outward,which may respectively mean facing generally toward or away from theimaginary center plane CP. Thus, on the left half of trailer 10, asurface which faces axially inward may be said to face generally to theright or rightward, and a surface which faces axially outward may besaid to face generally to the left or leftward. On the right half oftrailer 10, a surface which faces axially inward may be said to facegenerally to the left or leftward, and a surface which faces axiallyoutward may be said to face generally to the right or rightward.

Similarly, various components, surfaces etc. may be said to extendaxially inward or axially outward, which may respectively mean extendinggenerally toward or away from center plane CP. Thus, on the left half oftrailer 100, a component that extends axially inward may be said toextend generally to the right or rightward, and a component that extendsaxially outward may be said to extend generally to the left or leftward.On the right half of trailer 10 a component that extends axially inwardmay be said to extend generally to the left or leftward, and a componentetc. which extends axially outward may be said to extend generally tothe right or rightward.

Further explanation is provided with respect to references to thelongitudinal direction of trailer 100. Certain components of trailer 100are further forward or rearward of other components, or may be at thesame location along a longitudinal axis (where the longitudinal axisextends between front end 100 a and rear end 100 b. Thus, for example, areference to two points, surfaces, components or the like being “at thesame longitudinal position” or “at the same longitudinal location” meansthat the two points, surfaces, components or the like are at the sameposition along the longitudinal axis while they may be at differentaxial positions, that is, spaced to the left or right of one another, orspaced upwardly or downwardly of one another. Similarly, a reference totwo points, surfaces, components or the like being “longitudinallyadjacent” one another means that the two points, surfaces, components orthe like are at or adjacent the same position along the longitudinalaxis while they may be at different axial positions or spaced upwardlyor downwardly of one another. It is also noted that the term U-shaped orU-shaped configuration may be used herein to mean an upright U-shape orU-shaped configuration and the term inverted U-shaped configuration maybe used herein to mean an upside down U-shaped configuration.

Referring to FIGS. 6 and 7, front end housing 104 includes an exteriorwall 104 a that bounds and defines a front chamber 104 b. However,unlike the PRIOR ART front end housing 16, front end housing 104 oftrailer 100 does not include any openings in the exterior wall 104 athat will allow air to flow directly between the front chamber 104 b andthe air surrounding the exterior of trailer 100. (This is in contrast toPRIOR ART front end housing 16 which has a plurality of openings 16 cthat permit fluid communication between the air surrounding trailer 10and chamber 16 b.) Because front end housing 104 lacks openings similarto openings 16 c, front end housing 104 is sealed off from theatmosphere surrounding the tank assembly 102. An inlet 104 c (FIGS. 5.6. 7 and 9) is defined in the exterior wall 104 a and the purpose ofthis inlet 104 c will be discussed in greater detail later herein.

It will be understood that in some instances the front chamber 104 b maybe comprised of two or more chambers that are in fluid communicationwith each other but which are sealed from fluid communication with theair surrounding trailer 100. The front chamber 104 b is illustrated as asingle chamber for clarity of illustration only.

Central section 106 includes a circular exterior wall 106 a. Asindicated previously herein the exterior wall 106 a gives the tankassembly 102 a circular lateral cross-sectional shape when tank assembly102 is viewed either end 100 a, 100 b. Exterior wall 106 a bounds anddefines a generally circular interior space 106 b. An inlet 106 c isdefined in a top region of exterior wall 106 a proximate the top 100 cof trailer 100. Inlet 106 c may enter a top region of exterior wall 106a in central section 106 as shown in the illustrated embodiment in whichcase inlet 106 c is in fluid communication with first compartment 124.In other embodiments, the inlet may be defined in a top region of thefront end housing 104. As is evident from FIG. 6 an interior wallseparates the first compartment 124 from front chamber 104 b defined byfront end housing 104. In this instance, inlet 106 c may be is in fluidcommunication with first compartment 124 even though it appears from theexterior of the tank assembly 102 that inlet 106 c enters front endhousing 104.

The top region of exterior wall 106 a also defines one or more manholeopenings 106 d therein. Inlet 106 c and manhole openings 106 d are influid communication with interior space 106 b. Manholes 106 e extendupwardly and outwardly from the top region of exterior wall 106 a andcovers 106 f are selectively engageable with manholes 106 ee. Whencovers 106 f are removed then the manhole openings 106 d and therebyinterior space 106 b are in fluid communication with the air surroundingtrailer 100. When covers 106 f are engaged on manholes 106 e theninterior space 106 b is no longer in fluid communication with the airsurrounding trailer 100. In the figures, inlet 106 c is shown locatedforwardly of the forwardmost manhole 106 e but it will be understood theinlet 106 c may be provided in any suitable location on exterior wall106 a. The purpose of inlet 106 c will be described later herein.

Rear end housing 108 includes an exterior wall 108 a that defines a rearchamber 108 b. However, unlike the PRIOR ART rear end housing 20, rearend housing 108 of trailer 100 does not include any openings in theexterior wall 108 a that will allow air to flow between the rear chamber108 b and the air surrounding the exterior of trailer 100. (PRIOR ARTrear end housing 20 has a plurality of openings 20 c that permit fluidcommunication between the air surrounding PRIOR ART trailer 10 andchamber 20 b.) Rear end housing 108 is therefore sealed off from theatmosphere.

It will be understood that in some instances the rear chamber 108 b maybe comprised of two or more chambers that are in fluid communicationwith each other but which are sealed from fluid communication with theair surrounding trailer 100. The rear chamber 108 b is illustrated as asingle chamber for clarity of illustration only.

Trailer 100, like the PRIOR ART trailer 10 includes one or more hoppersthat extend downwardly from exterior wall 106 a and form part of centralsection 106. Trailer 100 is illustrated as including a first hopper 110,a second hopper 112, and a third hopper 114. (It will be understood thatfewer than three hoppers or more than three hoppers may be provided ontrailer 100.)

As best seen in FIGS. 2 and 2A the conical exterior wall of first hopper110 includes a front region 110 a and an opposed rear region 110 b. Anopening 110 c is defined at a bottom end of the conical exterior wall.The conical exterior wall of first hopper 110 bounds and defines aninterior space 110 d and opening 110 c is in fluid communication withinterior space 110 d. A valve assembly 116 (FIG. 5) is provided at abottom end of first hopper 110 and valve assembly 116 is movable betweenan open position and a closed position. Valve assembly 116 (FIG. 5) ismoved to the closed position to retain materials within first hopper 110and is moved to the open position to allow materials to flow throughopening 110 c and out of first hopper 110. Front region 110 a of theconical exterior wall of first hopper 110 angles forwardly and upwardlyand is welded at its uppermost end to an interior surface of the topregion of exterior wall 106 a. The front region 110 a forms a rearmostwall of front end housing 104.

Referring still to FIGS. 6 and 6A, the conical exterior wall of secondhopper 112 includes a front region 112 a and a rear region 112 b and anopening 112 c is defined in the bottom end of the conical wall. Theconical exterior wall of second hopper 112 also includes side regions112 e (FIGS. 7 and 7A) and 112 f that extend between front region 112 aand rear region 112 b. The conical exterior wall of second hopper 112bounds and defines an interior space 112 d and opening 112 c is in fluidcommunication with interior space 112 d. A valve assembly 116 (FIG. 5)is provided at a bottom end of second hopper 112 and valve assembly 116is movable between an open position and a closed position. Valveassembly 116 (FIG. 5) is moved to the closed position to retainmaterials within second hopper 112 and is moved to the open position toallow materials to flow through opening 112 c and out of second hopper112.

The conical exterior wall of third hopper 114 includes a front region114 a and a rear region 114 b. An opening 114 c is defined in the bottomend of the conical wall. The conical exterior wall of third hopper 114bounds and defines an interior space 114 d and opening 114 c is in fluidcommunication with interior space 114 d. A valve assembly 116 (FIG. 5)is provided at a bottom end of third hopper 114 and valve assembly 116is movable between an open position and a closed position. Valveassembly 116 (FIG. 5) is moved to the closed position to retainmaterials within third hopper 114 and is moved to the open position toallow materials to flow through opening 114 c and out of third hopper114. Rear region 114 b of third hopper 114 extends upwardly andrearwardly from the bottom 100 d of trailer 100 to the interior surfaceof a top region of exterior wall 106 a. Rear region 114 b is welded tothe interior surface of exterior wall 106 a and forms a rearmost wall ofcentral section 106 and a frontmost wall of rear end housing 108.

Referring to FIGS. 6-8, an upper end of rear region 110 b of firsthopper 110 and an upper end of front region 112 a of second hopper 112may be welded to each other and to a first interior rib 118. As shown inFIG. 8, first interior rib 118 extends transversely across the interiorof tank assembly 14 and is oriented at right angles to the longitudinalaxis of tank assembly 102. First interior rib 118 includes a first wing118 a and a second wing 118 b that are connected together by a concavelycurved bar 118 c. First and second wings 118 a, 118 b taper in widthfrom a widest region proximate bar 118 c to a terminal end 118 a′ or 118b′ respectively. It should be noted that a portion of each of the firstwing 118 a and second wing 118 b extends for a distance upwardly beyonda center point “A” of the circular-shaped exterior wall 106 a of centralsection 106. A space 118 d is defined between bar 118 c and the bottominterior surface of central section 106. Air is thus able to flowthrough space 118 d from a region on a front-facing side of interior rib118 through to a region on a rear-facing side of interior rib 118. Aweld pad 2 may be interposed between each of the first and second wings118 a, 118 b and the interior surface of the exterior wall 106 a ofcentral section 106.

A second interior rib 120 that is substantially identical to firstinterior rib 118 is located between second hopper 112 and third hopper116. Second interior rib 120 serves the same purpose as first interiorrib 118, namely, to strengthen the exterior wall while still permittingair to flow from front end housing 104 to rear end housing 108 and undercentral section 106.

It should be noted that where first hopper 110 and second hopper 112 arejoined together, one of the ribs, namely rib 107 b, is welded to theexterior surface of exterior wall 106 a of central section 106 and firstinterior rib 118 is welded to the interior surface of exterior wall 106a. A portion of the exterior wall 106 a is thus sandwiched between rib107 b and first interior rib 118. Similarly, where second hopper 112joins third hopper 114, one of the ribs, namely rib 107 c, is welded tothe exterior surface of exterior wall 106 a and second interior rib 120is welded to the interior surface of exterior wall 106 a. Thisarrangement ensures a structurally sound connection between adjacenthoppers 110, 112, 114.

A comparison between FIG. 1 which shows the PRIOR ART trailer 10 andFIG. 5 which shows the trailer 100 in accordance with the presentdisclosure reveals a number of things. Firstly, trailer 100 includes ribassembly 107 that comprises a plurality of circumferential ribs (i.e.circular ribs), namely ribs 107 a-107 d, instead of the invertedU-shaped ribs 38 a-38 d and horizontal bars 38 e of strengtheningassembly 38 provided on the PRIOR ART trailer 10.

Secondly, the first and second ribs interior 118 and 120 are locatedcompletely within the interior of the tank assembly 102. No portion offirst interior rib 118 or second interior rib 120 extends outwardlybeyond the bottom region of the exterior “skin” of the trailer 100. Thisis different to the PRIOR art trailer 10 where a portion of each of thefirst plate 28 and the second plate 30 extends downwardly for a distancebelow the bottom region of the exterior “skin” of trailer 10.

Thirdly, most of each of the first, second and third hoppers 110, 112,114 of the trailer 100 are located inside the exterior wall 106 a oftrailer 100. Consequently, only small portions of the conical walls ofthe first, second and third hoppers 110, 112, 114 forms part of theexterior “skin” of trailer 100. By contrast, in the PRIOR ART trailer10, most of each of the first, second and third hoppers 22, 24, 26extends from the upper wall 18 a and the conical walls of the hopperform part of the exterior “skin” of the trailer 10.

Fourthly, a part 106 a′ (FIGS. 5-8) of the exterior wall 106 a ofcentral section 106 extends around the outside of the conical walls ofeach of the first, second and third hoppers 110, 112, 114. For example,as can be seen in FIGS. 7 and 7A, part of the exterior wall 106 a′ isspaced a distance outwardly from side regions 112 e and 112 f of secondhopper 112 such that a gap 122 a is defined therebetween. Another partof the exterior wall 106 a′ extends between adjacent hoppers (such asbetween first hopper 110 and second hopper 112; and between secondhopper 112 and third hopper 114). The lower portions of each hopper 110,112, 114 thus extend outwardly from the part 106 a′ of exterior wall 106a. A middle chamber 122 (FIGS. 6 and 7) is therefore defined between theconical walls of first, second and third hoppers 110, 112, 114 and thepart 106 a′ of exterior wall 106 a. Gap 122 a forms part of this middlechamber 122. Middle chamber 122 thus not only surrounds part of theexterior surface of the conical wall of each hopper but also extendsbetween front end housing 104 and rear end housing 108. Front chamber104 b of front end housing 104 and rear chamber 108 b of rear endhousing 108 are thus placed in fluid communication with each other bymiddle chamber 122 (including gaps 122 a). Front chamber 104 b, middlechamber 122 and rear chamber 108 b together form a second compartment125 that is a sealed single chamber that is not in fluid communicationwith the air outside of trailer 100. By contrast, in the PRIOR ARTtrailer 10 there is no component similar to the middle chamber 122 oftrailer 100 and in trailer 10 the chamber 16 b and chamber 20 b arediscrete and separate and are not in fluid communication with eachother. Furthermore, neither of the chamber 16 b nor chamber 20 b issealed but both are, instead, open to the outside atmosphere.

Because front chamber 104 b, middle chamber 122 and rear chamber 108 bare in fluid communication with each other, when front chamber 104 b ispressurized (as is shown in FIG. 6 and as will be described laterherein), air flows from front chamber 104 b through middle chamber 122and into rear chamber 108 b. This air flow is indicated by the arrowsindicating airflow from the front of trailer 100 towards the rearthereof.

Referring to FIGS. 6 and 6A, interior space 106 b defined by exteriorwall 106 a, interior space 110 d defined by first hopper 110, interiorspace 112 d defined by second hopper 112 and interior space 114 ddefined by third hopper 114 form a first compartment 124 for tankassembly 102. First compartment 124 is suitable for carrying dry bulkmaterials therein. The one or more manholes 106 e provide a way for drybulk materials to be loaded into first compartment 124 and the openings110 c, 112 c, 112 d provide a way for those dry bulk materials to beremoved from first compartment 124.

An air piping system 126 is provided on trailer 100. Air piping system126 is provided to aid in the removal of the bulk load carried withinfirst compartment 124 of tank assembly 14. Air piping system 126 is alsoused to pressurize first compartment 124 and second compartment 125(formed by front chamber 104 b, middle chamber 122 and rear chamber 108b), as will be later described herein. The second compartment 125effectively forms part of the air piping system 126 in that secondcompartment 125 acts as a conduit that permits movement of air betweenfront end housing 104 and rear end housing 108 through middle chamber122. Second compartment 125 therefore aids in circulating air withintank assembly 102, particularly providing a conduit that is located atleast partially beneath first compartment 124. As has been discussedherein, first and second compartments 124, 125 share a common wall andair piping system 126 is provided to pressurize the air on both sides ofthat common wall.

Air piping system 126 provides the functions of aerating the bulkmaterial within first compartment 124 and flushing that bulk materialout of the hoppers 110, 112, 114 when tank assembly 102 is unloaded. Airpiping system 126 may be utilized to pressurize first compartment 124 inorder to apply downward pressure on the load of dry bulk materialretained within the first compartment 124 in order to aid in the removalof bulk material from first compartment 124. Air piping system 126simultaneously pressurizes the second compartment 125 for a number ofpurposes. Firstly, the substantial equalization of air pressure in firstand second compartments 124, 125 helps to reduce some of the stressesand strains on the joints between the various material sections thatform tank assembly 102. This may tend to increase the life of tankassembly 102. Secondly, the substantial equalization of pressure helpsreduce relative movement between the various sections of the tankassembly 102. Substantial pressure equalization between first and secondcompartments 124, 125 may particularly help to reduce relative movementbetween adjacent sections of the tank assembly 102, which are joinedtogether by a joint. In PRIOR ART trailers, there could be relativemovement between adjacent sections of the tank assembly 102 in theamount of about one quarter of an inch. With the introduction of thesubstantial pressure equalization in first and second compartments 124,125 as disclosed herein, the relative movement between adjacent sectionsof the tank assembly 102 (and tank assembly 202 as described laterherein) has been reduced down to a few thousandths of an inch, forexample around fifteen-thousandths of an inch movement would be typical.Because of the reduction in possible relative movement in the tankassembly 102 during loading and unloading because of the substantialequalization of pressure in first and second compartments 124, 125, thealuminum typically used to fabricate this type of tank assembly has beenable to be thinner than was required in PRIOR ART tank assemblies.Reducing the thickness of the aluminum (or other metal used duringfabrication) results in a tank assembly 102 and trailer 100 that weighsless than the PRIOR ART tank assembly or trailer. The reduction inrelative movement also requires that the material used to produce tanktrailer 102 need not be as strong as was required in PRIOR ART tankassemblies or trailers.

It should be noted that trailer 100 is not driven across the roads in apressurized condition. Air piping system 126 is only activated duringunloading of a load from first compartment 124 and is depressurized onceunloading is finished.

Air piping system 126 includes a plurality of different pipes, hoses,lines and valves (as will be discussed hereafter). Referring to FIGS. 5and 9 in particular, air piping system 126 includes, amongst othercomponents, an air intake pipe 128. Air piping system 126 may beselectively connected to a source of pressurized air. One suitablepressurized air source could be an air/pneumatic pump or compressor. Byway of example only, FIG. 5 shows a pump “P” that is provided foroperative engagement with the air piping system 126 on trailer 100. Pump“P” may be operatively engaged with a power take-off (PTO) on thetrailer or on the towing vehicle. (It should be understood that thispump “P” is representative of any suitable air source that may beengaged with air piping system 126.) Pump “P” may be mounted on thetowing vehicle or on a tractor or on tank assembly 102 or may be aself-contained unit that stands on the ground adjacent the trailer 100.For this reason, FIG. 5 (and FIG. 14) show pump “P’ spaced a shortdistance apart from trailer 100 (or trailer 200 in FIG. 14). Pump “P”typically will be located upstream of air piping system 126 and firstcompartment 124. Pump “P” is illustrated as having an air intake “P1”and an exhaust outlet “P2”. An operator may connect pump “P” by a hose(not shown) to first end 128 a of air intake pipe 128. In particular,the hose will connect first end 128 a of air intake pipe 128 to theexhaust outlet “P2” of pump “P”. Air expelled by pump “P” will be pumpedinto and flow through the hose and into the air piping system 126 viaair intake pipe 128. This air, provided under pressure by pump “P”, willbe used to pressurize first and second compartments 124, 125 asdescribed herein.

A top air pipe 130 extends off air intake pipe 128 and a first checkvalve 129 is engaged with air intake pipe 128 in a location betweenfirst end 128 a and top air pipe 130. Top air pipe 130 extends betweenair intake pipe 128 and inlet 104 c into front end housing 104. A sidebranch 133 extends off top air pipe 130 and side branch 133 terminatesin a blowdown pipe 134. A first valve 132 is engaged with top air pipe130 in a location between air intake pipe 128 and side branch 133. Asecond check valve 135 is engaged with side branch 133 in a locationbetween top air pipe 130 and blowdown pipe 134. Blowdown pipe 134extends from side branch 133, over the top 100 a of trailer 100 andenters first compartment 124 through inlet 106 c defined in exteriorwall 106 a. This is shown in FIGS. 6 and 6A. A terminal end 134 a ofblowdown pipe 134 is located within the interior first compartment 124.Terminal end 134 a defines an opening therein that enables blowdown pipe134 and first compartment 124 to be placed in fluid communication. Anemergency relief valve 136 is provided in blowdown pipe 134 and islocated between side branch 133 and inlet 106 c. A portion of blowdownpipe 134 extends downwardly from side branch 133 and this portion formsan exhaust pipe 138 that terminates in an outlet 138 a (FIG. 9) that isopen to the atmosphere. A second valve 140 is engaged with exhaust pipe138 in a location between side branch 133 and outlet 138 a.

First and second check valves 129, 135 permit air to flow in only onedirection through the pipe with which the check valve in engaged. Firstcheck valve 129 permits air to flow from first end 128 a of air intakepipe 128 in a direction towards top air pipe 130 and beyond but preventsair flow from top air pipe 130 in a direction back towards first end 128a. Second check valve 135 permits air to flow from top air pipe 130towards blowdown pipe 134 but does not permit flow in the reversedirection. Second check valve 135 helps to ensure that bulk material infirst compartment 124 does not accidentally flow through blowdown pipe134 and into second compartment 125 where it would accumulate and reduceor eliminate the possibility to provide substantially similar orsubstantially equal air pressure in first compartment 124 and secondcompartment 125.

First valve 132 and second valve 140 are each independently movablebetween an open position and a closed position. When first valve 132 isin the open position air may flow from air intake pipe 128 into andthrough top air pipe 130 and subsequently through inlet 104 c and intofront chamber 104 b of front end housing 104. Air will also flow fromtop air pipe 130 through side branch 133 and into blowdown pipe 134.Provided second valve 140 is closed, air will flow through upwardlythrough blowdown pipe 134, through inlet 106 c and into firstcompartment 124. If air is provided under pressure through air intakepipe 128 then pressurized air will flow into front chamber 104 b andfirst compartment 124. Front chamber 104 b and first compartment 124will be pressurized to the same extent; i.e., the air pressure in frontchamber 104 b and in first compartment 124 will be the same.

When first valve 132 is in the closed position, air does is unable toflow from air intake pipe 128 into and through top air pipe 130 or intoand through side branch 133 or blowdown pipe 134.

If second valve 140 is moved to the open position then air is able toflow out of first compartment 124 through blowdown pipe 134, throughexhaust pipe 138 and out of outlet 138 a and into the atmosphere. Secondvalve 140 may therefore be opened in order to depressurize firstcompartment 124. Because second check valve 135 is provided in sidebranch 133, when second valve 140 is moved to the open position, airwill also flow out of front chamber 104 b, back through top air pipe130. If first valve 132 is closed then the air flowing out of frontchamber 104 b will flow through side branch 133 and become entrainedwith the air flow toward exhaust pipe 138. So, opening second valve 140depressurizes first compartment 124 front chamber 104 b of front endhousing 104. Second check valve 135 prevents air flow from blowdown pipe134 back through side branch 133 through to top air pipe 130.

As has been discussed earlier herein, front chamber 104 b is in fluidcommunication with middle chamber 122 and with rear chamber 108 b ofrear end housing 108 and forms the sealed second chamber 125.Consequently, when air flows into front chamber 104 b under pressure,that air subsequently flows into middle chamber 122 and on into rearchamber 108 b. Pressurization of first compartment 124 and front chamber104 b also results in pressurization of middle chamber 122 and rearchamber 108 b. Depressurization of first compartment 124 and frontchamber 104 b also results in simultaneous depressurization of middlechamber 122 and rear chamber 108 b.

When pressurized air flows into the first compartment 124 and secondcompartment 125 (i.e., front chamber 104 b/middle chamber 122/rearchamber 108 b), then the air pressure moves in a same direction to wherethe air pressure on both sides of the conical walls of the hoppers 110,112, 114 tends to become substantially similar or substantially equal.Because of this substantially similar or substantially equalizedpressure, the walls bounding and defining first compartment 124 andhoppers 110, 112, 114 are under substantially less stress and strainthan would be the case if only the first compartment 124 was able to bepressurized and are less inclined to move relative to each other. Priorto moving the air pressure in the first compartment and the secondcompartment in the same direction, a force exerted by the air pressurein the first compartment might tend to cause a common section of wallbetween the two compartments to move. If the air pressure in the firstcompartment is higher, then the section of common wall might tend tomove outwardly and into the second compartment. If the air pressure inthe second compartment is higher, then the section of common wall mighttend to move inwardly into the first compartment. As the air pressuresin the first compartment and the second compartment move to a conditionwhere they tend to become substantially similar or substantially equal,then the forces on either side of the section of common wall tend toequalize and therefore movement in the section of common wall tends todecrease in magnitude.

When it is desired to depressurize first compartment 124, pump “P” isswitched off and first valve 132 is moved to the closed position andsecond valve 140 is moved to the open position. Air will then flow intoopening in the end 134 a of blowdown pipe 134, through blowdown pipe 134and out of exhaust pipe 138 to outside trailer 100.

If during operation the first compartment 124 and the front chamber 104b, middle chamber 122 and rear chamber 108 b reach a criticalpredetermined threshold, emergency relief valve 136 will beautomatically triggered and moved to an open position so that air canescape from top air pipe 130 and blowdown pipe 134. Emergency reliefvalve 136 may also be operatively linked to pump “P” to shut the sameoff if the valve 136 is triggered.

Referring still to FIG. 5, air piping system 126 further includes anaerator supply pipe 142 that originates at 142 a in air intake pipe 128and terminates at 142 b proximate rear end 100 b of trailer 100. Aeratorsupply pipe 142 is connected to an aerator (not shown) that is engagedwith each of the first, second and third hoppers 110, 112, 114. Theaerator may be any type of device that fluidizes the bulk materialretained within the associated first, second or third hopper 110, 112,114. For example, the aerator may be rubber fluidizing disc or anairsweep. Aerator hoses 144 extend between aerator supply pipe 142 andeach aerator. When activated, air will flow from air intake pipe 128,through aerator supply pipe 142, through the associated aerator hoses144, and aerator, and into the chamber of the associated hopper 110, 112or 114. This air flowing into the chamber of the hopper will stir up thebulk material in the chamber of the hopper in question. The air flowhelps to fluidize the bulk material so that the bulk material is morereadily able to flow out of an opening at the bottom of the associatedhopper 110, 112 or 114.

Air piping system 126 further includes a discharge pipe 146 thatoriginates in air intake pipe 128. A discharge valve 148 is engaged withair intake pipe 128 proximate a first end 146 a of discharge pipe 146and discharge valve 148 is movable between an open position and a closedposition. Discharge pipe 146 is also engaged with the valve assemblies116 located at the bottom end of each of the first, second and thirdhoppers 110, 112, and 114. Each valve assembly 116 is selectivelymovable between an open position and a closed position. Discharge pipe146 terminates in an open end 146 b that is located at a rear end 100 bof trailer 100. When one of the valve assemblies 116 is moved to theopen position, the chamber of the associated hopper 110, 112, or 114,and thereby first compartment 124, is placed in fluid communication withdischarge pipe 146. When the valve assembly 116 is moved to the closedposition then fluid communication between discharge pipe 146 and thechamber of the associated hopper 110, 112, or 114 and thereby with firstcompartment 124 is broken.

When discharge valve 148 is in the open position, discharge pipe 146 isplaced in fluid communication with air intake pipe 128 and air may flowfrom pump “P” through air intake pipe 128 and through discharge pipe 146under pressure. If the valve assembly 116 associated with first hopper110, for example, is moved to the open position, bulk material will flowout of the first compartment 124 through the valve assembly 116 of firsthopper 110 and into discharge pipe 146. The pressurized air flowingthrough discharge pipe 146 will entrain some of the bulk material andcause the bulk material to flow through discharge pipe 146 and out ofopen end of the discharge pipe 146 and through a hose attached theretoand into a storage compartment at the facility where the material isbeing unloaded.

Trailer 100 in accordance with the present invention is used in thefollowing manner. When trailer 100 arrives at a facility to be loadedwith particulate bulk material, trailer 100 is positioned so that atleast one of manholes 106 e is located directly under an opening of aloading hose or pipe. Cover 106 f of the at least manhole 106 e isremoved and dry, particulate, bulk material is loaded into firstcompartment 124 through the at least one manhole 106 e. Cover 106 f isthen replaced on each of the at least one manhole 106 e to seal firstcompartment 124. Trailer 100 is then driven across the roads to a secondfacility where the bulk particulate material is to be delivered.

The operator will connect a hose from a storage tank at the secondfacility to the end 146 b of discharge pipe 146 at rear end 100 b oftrailer 100. Discharge valve 148 is moved to the closed position if itis not already in that position. First and second valves 132 and 140 arealso placed in the closed position if they were not already in thatposition. A hose (not shown) is connected between pump “P” (FIG. 5) andfirst end 128 a of air intake pipe 128 and pump “P” is actuated. Airflows through air intake pipe 128 under pressure and, because dischargevalve 148 is closed, the air will flow into aerator supply pipe 128. Afirst one of the aerators may be activated so that air will flow fromaerator supply pipe 128, through aerator hoses 144 and through theassociated aerator to agitate the particulate material within theassociated hopper 110, 112 or 114. Air will therefore flow from airintake pipe 128, through aerator hoses 144, through the activatedaerator and into the chamber of the associated hopper 110, 112 or 114.While the aerator is activated, discharge valve 148 is moved to the openposition and the valve assembly 116 on the hopper 110, 112 or 114 thathas been aerated will be moved to the open position. (The aerator may bedeactivated prior to or after the valve assembly 116 on that hopper hasbeen moved to the open position.) The first valve 132 may also moved tothe open position so that air flows from air intake pipe 128, throughtop air pipe 130, through side branch 133 and blowdown pipe 134 and intothe upper end of first compartment 124 thereby pressurizing firstcompartment 124. At the same time as first compartment 124 is beingpressurized, air flows through top air pipe 130 and into the frontchamber 104 b of front end housing 104 and thereby into middle chamber122 and rear chamber 108 b. Front chamber 104 b, middle chamber 122 andrear chamber 108 b are therefore pressurized to the same extent as firstcompartment 124. When valve assembly 116 is moved to the open position,the fluidized bulk material retained in the opened hopper 110, 112 or114 flows out through the opened valve assembly 116 and into thedischarge pipe 146. Air flowing through discharge pipe 146 picks up thebulk material from the opened hopper and carries it through thedischarge pipe 146, out of the open end 146 b, and into and through thehose connected to the storage tank in the second facility.

When substantially all of the loose material in the first hopper hasflowed into the discharge pipe 146, the valve assembly 116 associatedwith that hopper will be closed as will the discharge valve 148. Theaerator associated with a next hopper will be activated and the processwill be repeated until that next hopper is substantially emptied. Thesteps will be repeated once again for the final hopper. It should beunderstood that it is possible in trailer 100 to activate more than oneaerator and open more than one hopper at a time.

When substantially all of the bulk material has been removed from thefirst compartment 124 through the three hoppers 110, 112, 114, dischargevalve 148 will be kept in the open position so that air continues toflow through discharge pipe 146. First valve 132 will also remain openso that air is moved from air intake pipe 128 through top air pipe 130into front chamber 104 b/middle chamber 122/rear chamber 108 b, andthrough side branch 133 and blowdown pipe 134 and into first compartment124. The air flowing into first compartment 124 through blowdown pipe134 will help dislodge any material that remains in any of the hoppers110, 112, 114. That dislodged material will flow into the discharge pipe146 and through the open end thereof and into the hose connectedthereto.

Pump “P” will be switched off and first valve 132 will be closed andsecond valve 140 will be opened to depressurize first compartment 124and front chamber 104 b/middle chamber 122 and rear chamber 108 b. Allvalves 132, 140 and 148 will then be closed and the hoses engaged withfirst end 128 a of air intake pipe 128 and with the open end ofdischarge pipe 146 will be disengaged. Trailer 100 is then free totravel back to the loading facility to take on its next load.

In summary, trailer 100 differs from trailer 10 in a number of respectsthat enable trailer 100 to be structurally stronger, lighter in weight(and therefore able to carry a heavier load) and to functionefficiently. Trailer 100 has a true cylindrical shape relative to thegenerally oval or elliptical PRIOR ART trailer 10. This true cylindricalshape (i.e. one that has a circular cross-section when viewed from thefront or back) is much stronger than an oval or elliptical shape becausea cylinder has fewer stress points than an ellipse or an oval.

PRIOR ART trailer 10 and trailer 100 in accordance with the presentdisclosure were tested for deformation and stress using a computerizedengineering analysis known as ANSYS® (ANSYS® is a registered trademarkof Ansys, Inc. of Canonsburg, Pa., USA). FIGS. 10 and 11 (which areexecuted in color) show an ANSYS® Deformation Comparison and FIGS. 12and 13 (which are executed in color) show an ANSYS® Stress Comparisonbetween PRIOR ART trailer 10 and trailer 100 of the present disclosure.

In the Deformation Comparison of FIGS. 10 and 11, areas of highestdeformation or movement are shown by the presence of red color and areidentified by the number 150. The high deformation areas 150 identifyregion of high movement even though trailer 10 includes strengtheningassembly 38 and first and second plates 28, 30. Areas of progressivelylesser deformation or movement are colored orange, then yellow, thengreen, then blue. Areas of the lowest deformation are colored dark blueand are identified by the number 152. FIG. 10 shows very clearly that inthe PRIOR ART trailer 10, despite the presence of strengthening assembly38 and plates 28, 30, the regions of highest deformation 150 are locatedon the front and rear regions of each hopper's conical wall, such asfront and rear regions 22 a, 22 b of first hopper 22. In particular, thehigh deformation regions 150 are located a short distance below thejoints where the hopper's conical walls join upper wall 18 a and firstand second plates 28, 30. The area of lowest deformation 152 on trailer10 is the upper wall 18 a.

By contrast, FIG. 11 shows trailer 100 has no obvious regions of highdeformation on the cylindrical wall 106 of tank assembly or on any ofthe hoppers 110, 112, 114 or adjacent any of the joints between wall 106and hoppers 110, 112, 114. In other words, there are no regions that arecolored red or orange. There is therefore less movement betweencomponent parts of trailer 100 than is the case with PRIOR ART trailer10. FIG. 11 shows that there are regions of lower deformation in trailer100 i.e., areas colored yellow and green that are identified by thenumber 154. These lower deformation regions 154 are located toward thebottom of tank assembly 102 where hoppers 110, 112, 114 exit the tankwall 106 and in regions located between first and second interior ribs118 and 120. Trailer 100 is therefor subject to less deformation thanwas the case with PRIOR ART trailer 10. This means in the real worldthat trailer 100 is stronger than PRIOR ART trailer 10 and thereforebetter able to withstand the rigors of transporting loads. Additionally,by substantially equalizing the pressure, thinner material can be usedto manufacture trailer 100, thereby substantially reducing the trailerweight and allowing the trailer 100 to haul more payload while stayingin compliance with highway motor laws.

Furthermore, front chamber 104 b, middle chamber 122 and rear chamber108 b are provided in regions of trailer 100 that might experience thelower deformation 154. The stresses that might be experienced in theselower regions of tank assembly 102 when first compartment 124 ispressurized tend to be offset by simultaneously pressurizing frontchamber 104 b, middle chamber 122 and rear chamber 108 b.

The cylindrical shape of outer wall 106 and the pressurization of areasbelow, in front of and behind first compartment 124 also enables themanufacturer to use thinner sheet material in the fabrication of trailer100 than is the case when producing the ovoid PRIOR ART trailer 10.Thinner metal may be used for trailer 100 because the metal and thejoints between the various components do not have to withstand the sameamount of relative movement as was the case in PRIOR ART trailer 10. Byway of example, trailer 100 is now about six-hundred pounds lighter thanPRIOR ART trailer 10 because of the thinning of the exterior “skin” andthe removal of various components of the strengthening assembly 38. Thefront end housing 104 on trailer 100 is also slightly differentlyconfigured to front end housing 16 of PRIOR ART trailer 10. Front endhousing 104 is more symmetrical than front end housing 16 and thepressurized area in and behind front end housing 104 will alsosubstantially reduce the weight and stress on the front end housing 104.

FIGS. 12 and 13 show an ANSYS® Stress Analysis of PRIOR ART trailer 10and an ANSYS® Stress Analysis of a trailer 100, respectively. Again,regions of highest stress in these two analyses are identified by thecolor red and progressively lower stresses are indicated by the colororange, then yellow, then green, then blue. In both PRIOR ART trailer 10and trailer 100 in accordance with the present disclosure, the maximumstresses are located where the hoppers join the wall that forms the restof the tank body i.e., upper wall 18 a in PRIOR ART trailer 10 and wall106 in trailer 100. In PRIOR ART trailer 10 the regions of maximumstress are identified by the number 156 and are clearly where the metalthat forms upper wall 18 a is welded to the metal that forms the hoppers22, 24, 26. The maximum stress measured at one of these regions 156 isshown on the left side of FIG. 12 to be 56,522.

FIG. 13 shows that the regions of maximum stress in trailer 100 are atthe joints where hoppers 110, 112, 114 are welded to wall 106. Theseregions are identified by the number 158. However, the maximum stressmeasured at one of these regions 158 is 30,454; so the maximum stressmeasured on trailer 100 is almost half of the maximum stress measured onPRIOR ART trailer 10.

FIGS. 14-18 show a second embodiment of a dry bulk trailer in accordancewith the present invention with the trailer being generally indicated at200. Trailer 200 is substantially identical to trailer 100 in structureand function with a few exceptions/additions that will be discussedhereafter in greater detail.

Trailer 200 comprises a tank assembly having a front end housing 104, acentral section 106 and a rear end housing 108 that are substantiallyidentical to front end housing 104, central section 106 and rear endhousing 108 of trailer 100. Central section 106 defines a firstcompartment 124 for carrying a load. Trailer 200 further includes asecond compartment 125 made up of front chamber 104 b defined by frontend housing 104, middle chamber 122 defined around regions of theexterior surfaces of first, second and third hoppers 110, 112, 114; andrear chamber 108 b defined by rear end housing 108. Front chamber 104 b,middle chamber 122 and rear chamber 108 b of trailer 200 are in fluidcommunication with each other in the identical manner to front chamber104 b, middle chamber 122 and rear chamber 108 b of trailer 100 andtherefore form a second compartment 125 that is sealed off from theatmosphere surrounding trailer 200.

Trailer 200 includes a rib assembly 207 that is welded to an exteriorsurface of central section 106. Rib assembly 207 is similar to ribassembly 107 in that it comprises a number of ribs that are spaced adistance longitudinally away from each other. Rib assembly 207 thereforincludes a first rib 207 a that is located adjacent a front end of firsthopper 110, a second rib 207 c that is located where first hopper 110joins second hopper 112, a third rib 207 e that is located where secondhopper 112 joins third hopper 114, and a fourth rib 207 g that islocated at a rear end of third hopper. These ribs 207 a, 207 c, 207 dand 207 g are substantially identical to ribs 107 a, 107 b, 107 c, and107 d, respectively, and are circumferential in nature. In other words,each of the first, second, third and fourth ribs 207 a, 207 c, 207 e,207 g is welded to the exterior surface of wall 106 a and circumscribesthe circumference of central section 106. Rib assembly 207, unlike ribassembly 107, also includes a fifth rib 207 b, sixth rib 207 d, andseventh rib 207 e that are welded to the exterior surface of wall 106 a.Fifth rib 207 b is located generally midway between first and secondribs 207 a, 207 c; sixth rib 207 d is located generally midway betweensecond and third ribs 207 c, 207 e; and seventh rib 207 f is locatedgenerally midway between third and fourth ribs 207 e and 207 g. Fifth,sixth and seventh ribs 207 b, 207 d, and 207 f are not circumferentialribs that circumscribe the circumference of central section 106 but areinstead generally C-shaped ribs. Fifth, sixth and seventh ribs 207 b,207 d, 207 f aid in providing additional strengthening to centralsection 106 of trailer 200 so that central section 106 is better able towithstand trailer 200 being placed under vacuum conditions, as will bedescribed later herein.

Trailer 200 also differs from trailer 100 in that the air piping system226 provided thereon is not only is useful for pressurizing first andsecond compartments 124, 125 of tank assembly 102 in a similar manner toair piping system 226 but, in addition, may be used to place first andsecond compartments 124, 125 of tank assembly 102 under a vacuumcondition. In particular, air piping system 226 may be used topressurize first compartment 124 and the chambers 104 b, 122 and 108 b,or may in other instances be used to place first compartment 124 andchambers 104 b, 122 and 108 b under vacuum. When vacuum is applied totank assembly 102, dry bulk material may be loaded into firstcompartment 124. When unloading tank assembly 102, pressure may beapplied to help remove a load of dry bulk material from firstcompartment 124. The simultaneous placing of chambers 104 b, 122 and 108b and first compartment 124 under vacuum helps to reduce some of thestresses and strains on the joints between the various sections of thetank assembly 202 and thereby aids in increasing the life of tankassembly 202. As with air piping system 126, activating air pipingsystem 226 (whether to pressurize the first and second compartments 124,125 or to create a vacuum therein) tends to reduce relative movementbetween component parts of tank assembly 202 (or trailer 200). This alsoaids in increasing the life of tank assembly 202.

Air piping system 226 includes a plurality of different pipes, hoses,lines and valves (as will be discussed hereafter). As discussed withreference to trailer 100, second compartment 125 also forms part of theair piping system 226. Air piping system 226 may be selectivelyconnected to a source of pressurized air or to a system that is capableof creating a vacuum condition. The device to which air piping system226 is operatively engaged may be one and the same device that is simplyused in two different ways. One suitable such device is theair/pneumatic pump or compressor represented by pump “P” in FIG. 14.Pump “P” may include an air intake port “P1” and an exhaust outlet “P2”.(It will be understood that any suitable pressurized air source orvacuum source may be utilized to cause air to flow through air pipingsystem 226 or to extract air therefrom.) Pump “P” may be mounted on thetowing vehicle or tractor or on tank assembly 202 or elsewhere such ason the ground adjacent the trailer 200. Pump “P” typically will belocated upstream of air piping system 226 and first compartment 124. Theair/pneumatic pump or compressor “P” may be used in a first state topressurize at least a part of air piping system 226. Furthermore, pump“P” may be used in a second state to remove air from within trailer 200.In particular, air piping system 226 may be engaged with the exhaust“P2” of pump “P” to provide a source of pressurized air through airpiping system 226. Air piping system 226 may, alternatively, beselectively connected to the air intake “P1” of pump “P” and, whenactuated, pump “P” will extract air from trailer 200 through air pipingsystem 226. Any type of vacuum system may be utilized instead of pump“P”. Pump “P” in FIG. 14 should be understood to be representative ofany suitable system that may be used to adjust (particularly tosubstantially equalize) the air pressure within first and secondcompartments 124, 125.

The specifics of air piping system 202 and its use will be described ingreater detail below.

Referring to FIGS. 14 to 17, air piping system 226 includes a coolingassembly 227 located proximate a front end 200 a of trailer 200. Coolingassembly 227 is mounted onto front end housing 104 by one or moremounting brackets 227 a and may include a radiator-type member with aplurality of fins and one or more cooling fans mounted between front end200 a and the radiator-type member. Cooling assembly 227 is particularlyuseful to cool down air that will be blown into first compartment 124during unloading. Air flowing from pump “P” used to pressurized firstcompartment 124 tends to be quite hot. If the bulk material carried inthe first compartment may be damaged by being heated (as would be thecase if the bulk material load is small plastic pellets, for instance),then the cooling assembly 227 ensures that at least some of the heatfrom pump “P” is at least somewhat extracted prior to contacting thebulk material.

An air intake pipe 228 is operatively engaged with cooling assembly 227and a number of pipes branch off air intake pipe 228 downstream ofcooling assembly 227. In particular, a top air pipe 230, an aeratorsupply pipe 242 and a discharge pipe 246 connect to air intake pipe 228.A discharge valve 248 is provided in air intake pipe 228 in a locationbetween where aerator supply pipe 242 and discharge pipe 248 connect toair intake pipe 228. Aerator hoses 244 extend between aerator supplypipe 242 and aerators on first, second and third hoppers 110, 112, 114.Aerator supply pipe 242 terminates in an end 242 a proximate rear end200 b of trailer. Discharge pipe 248 similarly terminates in an end 246a proximate rear end 200 b of trailer 200.

Referring to FIGS. 16A, 17A, 17B and 18, the parts of air piping system226 proximate front end 200 a of trailer 200 are shown in greaterdetail. Top air pipe 230 includes a top air valve 231 that is locatedbetween air intake pipe 228 and a branch pipe 233 in which top air pipe230 terminates. Branch pipe 233 is generally horizontally-oriented andtop air pipe 230 is generally vertically-oriented. Branch pipe 233terminates in a connector pipe 232 at a first end and in a blow-downpipe 234 at a second end. A first end of connector pipe 232 enters frontend housing 104 through inlet 104 c and is thereby placed in fluidcommunication in front chamber 104 b. Connector pipe 232 extendsdownwardly from inlet 104 c and then forwardly toward front end 200 a oftrailer 200 and ultimately connects to a filter 235. Filter 235 ismounted to front end housing 104 by way of a mounting bracket 235 a andmay be any suitable type of filter such as a spin flow filter. It shouldbe noted that filter 235 is utilized during pressurization of firstcompartment 124 and the second compartment during unloading of the bulkmaterial from first compartment 124 but is bypassed when firstcompartment 124 and the second compartment are placed under vacuumconditions during loading.

Connector pipe 232 includes a valve 237 and a check valve 239. Checkvalve 239 is positioned in a section of connector pipe 232 locatedbetween valve 237 and filter 235. An intake pipe 241 joins connectorpipe 232 at a location between valve 237 and check valve 239. Intakepipe 241 terminates in an end 241 a. (A cap or cover may be selectivelyplaced on end 241 a when not in use.) As shown in FIGS. 16A and 17B apipe 243 extends between filter 235 and cooling assembly 227.

As indicated above, branch pipe 233 connects to blowdown pipe 234. Acheck valve 245 (FIG. 16A) is located in branch pipe 233 between top airpipe 230 and blowdown pipe 234. Blowdown pipe 234 includes a firstsection 234 a (FIG. 16A that extends upwardly from branch pipe 233 andpasses through inlet 104 d defined in a top wall of front end housing104 but entering first compartment 124 (FIG. 15) of trailer 200.Blowdown pipe 234 is thereby placed in fluid communication with firstcompartment 124. A second section 234 b of blowdown pipe 234 extendsdownwardly from branch pipe 233 and terminates at an outlet 234 c thatis located a distance below an exterior surface of front end housing 104(FIG. 15). A valve 247 is located in blowdown pipe 234 in a positionbetween branch pipe 233 and outlet 234 c.

Air piping system 216 further comprises a plurality of pipes, valves,check valves etc. that are utilized mainly by the vacuum assemblyprovided on trailer 200. The vacuum assembly includes a filter assembly249 that is mounted by mounting brackets 249 a on a rear end housing 108proximate rear end 200 b of trailer 200. An exit pipe 251 that connectsto filter assembly 249 has a first end 251 a (FIG. 15) which extendsthrough a port 108 d defined in top portion of exterior wall 108 a oftrailer 200. Exit pipe 251 is thereby placed in fluid communication withfirst compartment 124. A second end 251 a of exit pipe 251 connects tofilter assembly 249 and is thereby placed in fluid communicationtherewith. As best seen in FIG. 16b , second end 251 a of exit pipe 251connects to a lower region of filter assembly 249. A valve is providedin exit pipe 251 in a location adjacent filter assembly 249 and therebycloser to second end 251 b than to first end 251 a of exit pipe 251.

A connector pipe 255 (FIG. 16B) has a first end 255 a that connects toan upper region of filter assembly 249 then extends forwardly and thendownwardly so that a portion of connector pipe 255 is orientedsubstantially vertically. A first branch pipe 257 extends outwardly fromconnector pipe 255 and enters rear end housing 108 of trailer 200through an entry port 108 c (FIG. 15). A bottom region of connector pipe255 turns through a right angle to form a second branch pipe 259 that islocated a distance vertically beneath first branch pipe 257. Secondbranch pipe 259 has an exit port 255 b that is located below a bottomsurface of rear end housing 108 of trailer 200 as can be seen in FIG.15. An emergency relief valve 261 is located between first and secondbranch pipes 257, 259. If during operation the first compartment 124 andthe front chamber 104 b, middle chamber 122 and rear chamber 108 b reacha critical predetermined threshold, emergency relief valve 261 will beautomatically triggered and moved to an open position so that air canflow into storage chamber, front chamber 104 b, middle chamber 122 andrear chamber 108 b through connector pipe 255. Emergency relief valve261 may also be operatively linked to pump “P” to shut the same off ifthe valve 261 is triggered.

A first valve 263 is located on connector pipe 255 between relief valve261 and second branch pipe 259. A second valve 265 is located onconnector pipe between first branch pipe 257 and first end 255 a. Afilter pipe 269 extends downwardly from a bottom of filter 249. Bulkmaterial may be sucked into exit pipe 251 during loading and therebyflow into filter 249. This bulk material may clog filter 249. Filterpipe 269 may be used to blow air or any accumulated dust or particulatematter out of filter 249. It should be noted that filter 249 is onlyutilized when vacuum is applied to trailer 200 during a loadingoperation. Filter 249 is bypassed when first compartment 124 and thesecond compartment (front compartment 104 b, lower compartment 122 andrear compartment 108 b) are pressurized.

A fill pipe 271 extends through a first inlet 108 e defined in rear endhousing 108 and through a second inlet 106 h defined in rear region 114b. Consequently, a first portion of fill pipe 271 is located withinfirst compartment 124, a second portion of fill pipe 271 is locatedwithin rear chamber 108 b, and a third portion of fill pipe 271 islocated outside of the exterior surface of trailer 200. Fill pipe 271has a first end 271 a (FIG. 15) located in first compartment 124 and asecond end 271 b that is located outside of the exterior surface oftrailer 200 (FIG. 16B).

Air piping system 226 is used on trailer 200 as follows. When it isdesired to load bulk material into first compartment 124, the vacuumassembly is utilized. A hose (not shown) will be connected to second end271 b of fill pipe 271 and will further be connected to a storagecontainer containing a quantity of bulk material to be loaded intotrailer 200. The storage container, for example, may be a rail car.

Referring to FIGS. 15 and 16A, various valves and check valves proximatefront end 200 a and rear end 200 b of trailer 200 need to be set atappropriate positions for vacuum conditions to be applied to trailer200. Check valves 239 and 245 (FIG. 16A) are moved to a closed position.The closed position is indicated in FIG. 16A by an “x” being placed oncheck valve 245. The “x” on check valve 239 is not able to be seen inFIG. 16A because of the orientation of the valve in the figure. Checkvalve 245 closes when trailer 200 is placed into a vacuum condition sothat bulk material cannot flow down blowdown pipe and into the frontchamber 104 b and thereby begin to accumulate in second compartment 125.Check valve 239 is also closed when trailer 200 is placed into a vacuumcondition to ensure bulk material cannot flow into filter 235 or coolingassembly 227. When trailer 200 is to be placed under vacuum, top airvalve 231 and valve 247 are also moved to a closed position (indicatedby the “x” on each valve). Valve 237 is moved to an open position(indicated by the fact that no “x” is illustrated on the valve in FIG.16A). Referring to FIG. 16B, first valve 263 is moved to the closedposition (indicated by the “x”), second valve 265 and valve 253 aremoved to the open position (indicated by the lack of an “x”).

As indicated previously herein, pump “P” (FIGS. 5 and 14) may beprovided on the vehicle towing tank trailer 200 or mounted on trailer200 itself or be placed on the ground adjacent trailer 200. Pump “P” mayinclude an air intake “P1” and an exhaust outlet “P2”. An operator mayconnect pump “P” by a hose (not shown) to first end 241 a of intake pipe241. The operator will connect the hose to air intake “P1” if he or shewishes to create a vacuum in the first and second compartments 124, 125or will connect the exhaust “P2” on pump “P” to pressurize first andsecond compartments 124, 125.

It should be noted that in trailer 200 the single intake pipe 241 isused to connect air piping system 226 to pump “P”. In PRIOR ART trailersthat have included an air system for pressuring a trailer storagecompartment and/or providing a vacuum therein, a source of pressurizedair would have to be connected to a first inlet on the trailer and thevacuum source would have to be connected to a second inlet on thetrailer. Typically, in these PRIOR ART trailers the first inlet would belocated proximate a first end of the trailer and the second inlet wouldbe provided proximate a second end of the trailer. The operator wouldtherefore have to drag a long heavy hose to connect it to the firstinlet when the trailer was to be pressurized and would have to detachthe hose and move it to the other end of the trailer if the trailer wasto be placed under vacuum. In trailer 200 in accordance with the presentdisclosure, the hose can remain attached to the same single intake pipe241 and it is simply the valves on trailer 200 that are switched(manually and/or automatically) to switch the air piping system 226 fromone that creates a vacuum in the trailer 200 to one that pressurizes thetrailer 200. This greatly reduces the effort and time involved forloading and unloading a trailer 200 in accordance with the presentinvention relative to PRIOR ART TRAILERS.

Referring to FIGS. 16A and 16B, in trailer 200, air piping system 226may be actuated to create a vacuum in first compartment 124 to load bulkmaterial therein. Pump “P” is actuated and begins to draw air throughintake pipe 241 and out of first end 241 a thereof. Movement of air inthe direction of arrow “B” through intake pipe 241 causes air to bedrawn through connector pipe 232 towards intake pipe 241 and therebydraws air out of front chamber 104 b of trailer 200. As air flows out offront chamber 104 b through connector pipe 232, air is drawn through thesecond compartment 125 created by front chamber 104 b, middle chamber122 and rear chamber 108 b. This air flow through second compartment 125is indicated by arrows “C” in FIGS. 16A and 16B and in FIG. 15.

Referring to FIG. 16B, as air flows out of rear chamber 108 b and intomiddle chamber 122 towards front chamber 104 b, air is drawn throughfirst branch pipe 257 and down connector pipe 255 in the direction ofarrow “D”. This air flow through connector pipe 255 draws air throughfilter 249 in the direction of arrow “D” which pulls air into lowerregion of filter 249 from exit pipe 251. Air is pulled through exit pipe251 in the direction of arrow “E” and cause air to be sucked out offirst compartment 124 through first end 251 a in the direction of arrow“F” (FIG. 15). Continued operation of pump “P” will begin to evacuateall of the air from first compartment 124, setting up a vacuum conditiontherein. It should be noted that at the point a vacuum condition exitsin the first compartment 124 it also is substantially simultaneouslycreated in second compartment 125. The air pressure on the either sideof the common wall separating the first compartment 124 from the secondcompartment 125 is thus substantially equal. Because of this there isvery little relative movement between the various components that makeup of trailer 200 and very little stress or stress placed on thesecomponents during the loading operation of bulk material which will bedescribed below. Furthermore, because of the reduction in stress, strainand movement, the thickness of the walls that bound and define firstcompartment 124 and second compartment 125 can be fabricated fromthinner metal than would be required if second compartment 125 was notplaced under vacuum along with first compartment 124.

It should further be noted that the movement of valves 253 and 263between a closed position and an open position is preferably automated.Automatic operation of valves 253, 263 may be desirable because of theheight at which the two valves are positioned on trailer 200. It will beunderstood that the valves 253, 263 may instead be manually controllableby the operator. The operator does not need to climb up on to the truckto shift these valves between the open and closed position. The operatormay be provided with a handheld controller when he or she canelectronically operate valves 253, 263 and one or more or all of theother valves on trailer 200.

If valves 253, 263 open automatically, when pump “P” is actuated tocreate a vacuum condition within first compartment 124 and as the air issucked through connector pipe 255 in the direction of arrow “D” andcontacts valve 265, valve 265 will moves automatically to the openposition. This movement of valve 265 may automatically trigger openingof valve 253. Alternatively, the movement of air as it is sucked out ofexit pipe 251 and into filter 249, may cause valve 253 to automaticallymove to the open position. (Similarly, when trailer 200 is pressurizedduring unloading as will be described hereafter, as air flows in areverse direction to arrow “D” and contacts valve 265, valve 265 maymove to the closed position and valve 253 may then also be automaticallytriggered to move to a closed position.)

The vacuum condition in first compartment 124 will cause air to be drawninto first compartment 124 through fill pipe 271 in the direction ofarrow “G” (FIG. 15). As indicated earlier herein, second end 271 b offill pipe 271 is connected via a hose to a storage container which has aquantity of bulk material therein. As air flows through fill pipe 271 inthe direction of arrow “G” to try and neutralize the vacuum condition infirst compartment 124, bulk material becomes entrained in the airflowing through hose connected to second end 271 b and is sucked intofill pipe 271. The bulk material flows through fill pipe 271 and becomesdeposited into first compartment 124. As the first compartment 124 fillswith bulk material, the vacuum pressure in fill pipe 271 drops to thepoint that no further bulk material is drawn into fill pipe 271. Sincetrailer 200 does not travel in a vacuum condition, first valve 263 ismoved to the open position. This allows air to flow back into connectorpipe 255 and thereby into first compartment 124 and into the secondcompartment (i.e., rear chamber 108 b, middle chamber 122 and frontchamber 104 b). Pump “P” will also be deactivated and all the variousvalves and check valves will be moved to a position that prevents bulkmaterial from escaping from first compartment 124 or contaminantsentering the second compartment.

In some embodiments, such as is illustrated in FIG. 17C, trailer 200 maybe provided with more than one fill pipe 271. FIG. 17C shows two fillpipes 271, 271 that extend rearwardly from the rear end 200 b of trailer200. Each of the two fill pipes 271, 271 extends into first compartment124 and has a first ends 271 a that is located within first compartment124. Each of the two fill pipes has a second end 271 b that may beselectively connected via a hose to a storage bin containing a quantityof bulk material. The difference between the two fill pipes 271, 271 isthat the one fill pipe is longer than the other. The difference betweenthe two lengths is related to how much of each fill pipe 271, 271 islocated within first compartment 124. FIG. 15 shows one of the fillpipes 271 where the first end 271 a thereof is located closer to frontend 200 a of trailer 200 than to the rear end 200 b thereof. It shouldbe understood that the second fill pipe 271 may have its first end 271 alocated closer to the rear end 200 b of trailer 200 than to front end200 a thereof. This difference in the location of the first ends 271 awithin first compartment 124 helps to ensure a quicker and easierloading of first compartment 124. The longer fill pipe 271 that has afirst end 271 a closer to the front end 200 a of trailer 200 will beconnected to the storage bin first to load the front region of firstcompartment 124. The operator will then move the hose connecting thetrailer 200 to the storage bin to the shorter second fill pipe 271 andthen load the rear region of the first compartment 124. This methodhelps to progressively fill first compartment 124 in a way that tends toreduce the likelihood there will be a reduction in vacuum pressureduring loading. If vacuum pressure drops below a certain level, then airflow through fill pipe(s) 271 may be insufficient to suck bulk materialfrom the storage bin or to move bulk material through fill pipe(s) 271.It should also be noted that if filter 249 becomes clogged, vacuumpressure may drop to a point that loading through fill pipe 271 slows orceases. Filter 249 has to be cleaned regularly to ensure sufficientvacuum pressure is available for loading first compartment 124 with bulkmaterial.

When the trailer 200 reaches its destination and it is time to unloadthe bulk material from trailer 200, both the first compartment 124 andthe second compartment are pressurized in a similar manner as to whathas been described with respect to trailer 100. Referring to FIG. 16B,valves 253 and 263 are moved to the closed position to enablepressurization of first compartment 124, front chamber 104 b, middlechamber 122 and rear chamber 108 b.

Referring to FIG. 17A, check valves 239 and 245 are moved to the openposition. Top air valve 231 is moved to the open position and valves 237and 247 are moved to the closed position (as indicated by the “x”). Itshould be noted that check valve 245 is open when top air valve 231 isopen so that air may flow into blowdown pipe 234 but bulk materialcannot move in the opposite direction.

A pump is connected to first end 241 a of intake pipe 241. Air flowsfrom pump “P” into intake pipe 241 in the direction of arrow “H”. Fromintake pipe 241, air flows through check valve 239, through filter 235,through pipe 243, through cooling assembly 227, and into discharge pipe228. Air flows through discharge pipe 228 and when the air flow reachestop air pipe 230, some of the air flows into top air pipe 230 and someflows through discharge pipe 228. The air flow into top air pipe 230 isindicated by arrow “I”. The air flow “I” splits where top air pipe 230connects to branch pipe 233 and some air flows through branch pipe 233and into connector pipe 232. Since valve 237 is closed, the air flowsupwardly through connector pipe 232 and into front chamber 104 b andsubsequently into middle chamber 122 and rear chamber 108 b.

Air also flows through branch pipe 233, through check valve 245 and intoblowdown pipe 234 a. The air flowing into first compartment 124 fromblowdown pipe 234 applies pressure onto the dry bulk material carried infirst compartment 124 forcing the material downwardly toward the first,second and third hoppers 110, 112, 114.

The valve 248 (FIG. 14) in discharge pipe 228 may initially be placed ina closed position so that air flowing through discharge pipe 228 beyondtop air pipe 230 will be diverted into aerator supply pipe 242, throughaerator hoses 244 and into the aerator on first, second or third hopper110, 112, 114 as has been described with respect to trailer 100. Whenvalve 248 is moved to the open position, air will also flow throughdischarge pipe 246 and as each valve assembly on the associated hopper110, 112, 114 is opened, bulk material will be flow into discharge pipe246 and become entrained in the air flowing therethrough and will flowinto a hose connected to end 246 a of discharge pipe 246. Once all thebulk material has been unloaded from the pressurized first compartment124, valve 247 is opened so that first compartment 124 and the secondcompartment will be depressurized and will return to atmosphericpressure.

It has been disclosed herein that the second compartment comprises frontchamber 104 b of front end housing 104; middle chamber 122 (and 122 a)and rear chamber 108 b of rear end housing 108 that are all in fluidcommunication with each other and are all pressurized or placed undervacuum when the first compartment for the load is pressurized or placedunder vacuum. However, in other embodiments a divisional wall may beprovided between front chamber 104 b and middle chamber 122 and/orbetween rear chamber 108 b and middle chamber 122 and only one or two offront chamber 104 b, middle chamber 122 (with 122 a), or rear chamber108 b may be pressurized or placed under vacuum with the firstcompartment.

It is further contemplated that in yet other embodiments, additionalchambers or compartments may be provided exteriorly of the firstcompartment and those additional chambers or compartments may be placedunder pressure in one embodiment or under vacuum in another embodiment.It is further contemplated that in other examples, the second firstcompartment may comprise a layer of sheet material that is appliedaround substantially the entire exterior surface of the wall thatdefines the first compartment such that a gap is formed between thelayer of sheet material and the wall that defines the first compartment.Pressurized air might be pumped into that gap in one embodiment and avacuum might be applied to that gap in other embodiments. In thisinstance, the wall surrounding the entire first compartment (except forthe manholes and inlets) may have substantially similar or substantiallyequal pressure or substantially similar or substantially equal vacuumapplied to both sides of the wall and the wall will therefore be undersubstantially constant pressure.

It should be understood that the terms “substantially similar” and“substantially equal” are utilized herein as representing a state wherethe air pressures in the first and second compartments tend to move asclose as physically possible to the same pressure or state of vacuum.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes and are intended to be broadlyconstrued.

Moreover, the description and illustration of the preferred embodimentof the disclosure are an example and the disclosure is not limited tothe exact details shown or described.

1. A method of unloading dry bulk materials from a dry bulk tankcomprising: providing a dry bulk tank including a first compartment anda second compartment; wherein the first and second compartments arelocated on opposite sides of a portion of a common wall of the dry bulktank; unloading the dry bulk materials from the first compartment; andsubstantially equalizing air pressure in the first and secondcompartments during unloading.
 2. The method as defined in claim 1,further comprising: placing the first compartment and second compartmentin fluid communication with each other.
 3. The method as defined inclaim 2, further comprising connecting an air piping system between thefirst compartment and the second compartment.
 4. The method as definedin claim 1, wherein the substantially equalizing of air pressure in thefirst and second compartments comprises causing air to flow underpressure into the first compartment and the second compartment.
 5. Themethod as defined in claim 4, wherein the causing of air to flow underpressure into the first compartment and the second compartment occurssubstantially simultaneously.
 6. The method as defined in claim 1,further comprising: connecting an air intake pipe of an air pipingsystem to an exhaust of a pump; connecting the first compartment and thesecond compartment to each other with the air piping system; activatingthe pump; and causing air to flow into the first compartment and thesecond compartment.
 7. The method as defined in claim 6, wherein causingair to flow into the first compartment and the second compartmentcontinues until air pressure in both of the first and secondcompartments is from about 10 Psi up to about 15 Psi.
 8. The method asdefined in claim 6, further comprising; providing a cooling assembly inthe air piping system; passing air from the pump through the coolingassembly; and cooling the pumped air with the cooling assembly.
 9. Themethod as defined in claim 8, further comprising: causing the cooled airto flow into the first compartment and the second compartment.
 10. Themethod as defined in claim 8, further comprising: positioning a checkvalve between the air intake pipe and the cooling assembly; permittingair to flow from the air intake pipe through the check valve to thecooling assembly when the pump is activated; and preventing air fromflowing from the cooling assembly to the air intake pipe with the checkvalve.
 11. The method as defined in claim 10, further comprising:positioning a filter between the check valve and the cooling assembly;and filtering air flowing from the check valve to the cooling assemblywith the filter.
 12. The method as defined in claim 8, furthercomprising: connecting a discharge pipe to the cooling assembly;operatively engaging the discharge pipe with a valve assembly connectedto the first compartment; opening the valve assembly; causing bulkmaterials to flow out of the first compartment and into the dischargepipe; entraining the bulk materials in air flowing through the dischargepipe; and removing the bulk materials from the tank trailer through thedischarge pipe.
 13. The method as defined in claim 8, furthercomprising: connecting a discharge pipe to the cooling assembly;operatively engaging the discharge pipe with a valve assembly connectedto the first compartment; connecting a top air pipe to the dischargepipe; connecting the top air pipe to the second compartment; and causingair to flow from the discharge pipe through the top air pipe and intothe second compartment.
 14. The method as defined in claim 13, furthercomprising: providing a top air valve in the top air pipe; and movingthe top air valve to an open position prior to causing air to flow fromthe discharge pipe.
 15. The method as defined in claim 13, furthercomprising: connecting a blowdown pipe to the top air pipe; connectingthe blowdown pipe to the first compartment; and causing air to flow fromthe top air pipe, through the blowdown pipe and into the firstcompartment.
 16. The method as defined in claim 15, further comprising:positioning a valve between the top air pipe and the blowdown pipe; andopening the valve between the top air pipe and the blowdown pipe priorto causing air to flow from the top air pipe through the blowdown pipeand into the first compartment.
 17. The method as defined in claim 16,wherein the positioning of the valve between the top air pipe and theblowdown pipe comprises providing a second check valve and positioningthe second check valve in the top air pipe.
 18. The method as defined inclaim 17, further comprising: permitting air to flow through the secondcheck valve from the top air pipe to the blowdown pipe when pressurizingthe first and second compartments.
 19. The method as defined in claim17, further comprising: preventing air from flowing through the secondcheck valve from the blowdown pipe to the top air pipe when the pump isdeactivated.
 20. The method as defined in claim 17, further comprisingpreventing particulate matter entrained in air flowing through theblowdown pipe from entering the top air pipe using the second checkvalve.
 21. The method as defined in claim 17, further comprising:providing a section of the blowdown pipe that terminates outside of anexterior wall of the dry bulk tank; deactivating the pump; and causingair to flow from the first compartment through the section of theblowdown pipe and to the outside of the exterior wall of the dry bulktank; and depressurizing the first compartment.
 22. The method asdefined in claim 20, further comprising: providing an exhaust valve inthe section of the blowdown pipe; and moving the exhaust valve from aclosed position to an open position prior to causing air to flow throughthe section of the blowdown pipe.
 23. The method as defined in claim 22,further comprising: moving the exhaust valve from the open position tothe closed position prior to pressurizing the first compartment.
 24. Themethod as defined in claim 22, further comprising: causing air to flowfrom the second compartment through top air pipe and down the section ofthe blowdown pipe when the exhaust valve is moved from the closedposition to the open position.
 25. The method as defined in claim 13,wherein the connecting of the top air pipe to the second compartmentincludes extending a connector pipe between an inlet into the secondcompartment and the air intake pipe; and providing a valve in theconnector pipe between the inlet and the air intake pipe; moving thevalve in the connector pipe from an open position to a closed positionprior to causing air to flow from the top air pipe to the blowdown pipe.26. The method as defined in claim 25, further comprising: moving thevalve in the connector pipe from the closed position to the openposition; and evacuating air from the second compartment through theconnector pipe and out the air intake pipe.
 27. The method as defined inclaim 1, further comprising: moving air in a same direction through thesecond compartment from a first end of the dry bulk tank to a second endof the dry bulk tank when a pump is actuated; and pressurizing the firstcompartment and the second compartment.
 28. The method as defined inclaim 27, further comprising: moving air in a second direction throughthe second compartment from the second end of the dry bulk tank to thefirst end of the dry bulk tank when the pump is moved from a first stateto a second state; and creating a vacuum in the first compartment andthe second compartment.